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Criticizing other people's figures on my webpage
A few months ago I started collecting papers that contain figures I think convey information in a very efficient manner (i.e., figures that I think are very well illustrated and that should serve as examples of how they should be designed).
Now, because I am a huge data-vis geek, I have been thinking about opening a page on my website in which I talk about how I think figures should be designed and which principles I expect students/coauthors/general public to follow when illustrating data. Consequently, I am inclined towards including some of those amazing figures I have been collecting and talking about them (i.e., why they are efficient and well designed). More controversially, perhaps, is the fact that I also plan to include some figures that I believe were terribly designed and explain in which ways they fail (some of those badly designed figures are actually mine).
While I will seek the adequate rights to post them on my blog (e.g., through RightsLink for Elsevier journals), I would like to hear about the morality of this practice, particularly due to the fact that I will negatively criticize other authors' work.
Is there any moral (or even legal) problem in criticizing other people's figures on my website? Should I expect any sort of retaliation if I decide to do that? I understand that this is largely dependent on the tone I employ, but I will make every effort to be as technical and objective as possible.

Can you be identified through your blog?

A solution to the problem of criticizing other people's figures might be to design the bad figures yourself with arbitrary data. This way you won't hurt anybody's feelings.

@101010111100 yes, I can be identified. It's linked to my academic webpage.

@DavidZwicker I like your solution, I will think about it. But it's usually important to structure this sort of criticism behind data that actually convey information in order to show how difficult it is to interpret the data out of it. But I think your suggestion may be a good alternative in order to avoid any future hassle.

@DavidZwicker Can you turn your comment into an answer so that I can vote it up?

Some people might voluntarily provide figures they have made for you to critique.

I love the idea. I think it would be a great opportunity to learn a thing or two. But I can see how that would upset a lot of people.

Like it.  I had a similar idea regarding papers.  I wanted to shame and name poorly written papers.

An advantage to @DavidZwicker proposal is that you can then correct the figure to practically show how your suggestion improves it.

One shall publish data for the sole purpose of being criticized. Otherwise what would be the point in scientific publishing?

There is, in fact, a website that does something similar (although it tends to use visualisation from the media rather than literature), and it's an extremely useful resource - http://junkcharts.typepad.com/ - if your website is good it will be useful to people.

Generating your own bad graphs to criticize seems to me like it has no where near the power of illustrating issues on real graphs.

I agree with @Jeff   Use the graphs you want, but insert garbage data, just enough to make your point known.  Graphs are graphs, as in the current gossip involving presidential cakes and plagiarism, I have never heard of trademarked or copyrighted graphs.  Their content however is totally different.

I would actually love to read that blog, even if it had work of mine.

"Is there any moral (or even legal) problem in criticizing other people's figures on my website?" You might be wrong. "Should I expect any sort of retaliation if I decide to do that?" Definitely. Retaliation is human.

Bad examples are as important as good examples. The only question is if they all should be made up based on real-life examples (more effort) or if you can just take real life examples and the authors of the bad real life examples have to life with the eternal shame of being singled out when there would maybe be tons of others even worse examples.

Could you link to your blog? I would find this kind of article interesting and useful.

You would be doing these people a disservice by not criticizing their work. Also, reviewing bad visualizations is not something new, Stephen Few has written entire books tearing apart bad examples.

If you are in the US, and the figures were produced by US authors, could the critique be considered "Fair Use"?

I can't even imagine a situation in which criticizing published academic materials on their merits would be wrong or immoral.
How would it be different from criticizing someone's selection of an econometric or statistical model to use on their data?  This happens constantly in academic literature, and in fact is crucial to the process of research.  The way data is conveyed to others through graphs is no less important than model selection, and both can be used to deceive or obscure.
So as long as you cover two bases:

Avoid ad hominem attacks, as you should in all sorts of reviewing, and
Follow any copyright rules the publishers impose,

Not only is there nothing wrong with doing it, I would argue that as an academic and data viz expert, you should do it.  As for someone taking offense at your criticism?  Well, as long as you're professionally criticizing its merits and avoiding problem number 1 from above then it's you who are in the right, and the one taking offense who is in the wrong.

The difficulty would be convincing those whose work you criticise thatyou're not just making an aesthetic judgement.

@ChrisH Dataviz may be new relative to most fields, but it's got enough substance to it to have gone well beyond mere aesthetics.  I don't think this has penetrated most of academia though, and is more the realm of data scientists at the moment.  That should definitely be something we try to change.

I didn't say convincing me, I said convincing those whose figures you're looking at. Online criticism from an upstart may not help your own position. Related experience: trying to convince people to use colourmaps that work for colourblind people (or B&W reproduction) and that don't have arbitary discontinuities is often treated as an aesthetic issue.

@ChrisH It is a problem (says your typographer). How to overcome it? Collect examples where poor typography, dataviz, English grammar or whatever is not just cumbersome; rather it's invalidating the work, or even, changing its meaning. These are the points where you have to convince people you're not just a XYZ-nazi. Oh btw, https://xkcd.com/1184/

In some jurisdictions (such as the United States), you may have a legal right to copy the figures for the purpose of commentary, without regard to any copyright rules the publishers purport to impose.

I am not even going to address morality, as that can be a minefield.
Legality can hinge upon where you live.  In the USA free speech/free expression would allow for criticism of others works, but be aware that this is a double edged sword.
I would be careful about how you go about picking apart visualized data by others.  Be very sure to only go about analyzing the structure/what has been shown, and not to slander the person who created the data visualization.
The thing is, everyone will offend someone somewhere, somehow, sometime.  The important thing is that we try to keep the amount of offenses to a minimum.  The best way to do this in my opinion, would be that make sure to state that your preferences are just that, preferences.
When we start calling our opinions facts, we start running into problems.  I have first hand experience in this, being one with Asperger's Syndrome. I have delusions of "my opinion is the only opinion" thing... and it does not go over well. (and is something I am constantly working on)

Definitely.  The freedom of opinion is very fundamental.  (It's not even a matter of how opinions are phrased so much as the fact that there is a fundamental difference between a FACT and an OPINION.  Not everyone has sufficiently high sanity or skill to recognize this difference.)

The thing is, dataviz isn't just "preferences".  It's a field complete with experts, published work, and core tenants.  I might even go so far as to say its subjective elements are very similar to the subjective elements of empirical research, such as control variables and model selection.  Unfortunately I think it's common for academics to be entirely unaware of this.

@Jeff  I will have to look into dataviz more then.  I was going more on the line "how I think figures should be designed."

Not a good idea.  You may mean well but you may offend others, irrespective of the tone or how constructive your criticism is meant to be.  People from different cultures react in different ways to criticism, and there is little to no upside in even annoying one person.  In addition, if the figures are copyrighted you might get some flak.
It is infinitely better to highlight outstanding examples.

Comments are not for extended discussion; this conversation has been moved to chat.

This sounds silly to me. We should stop all criticisms because some culture might be offended? That sounds like an argument to end all science.

@ff524 I wasn't discussing anything, I was referring to the original question in my comment. I was commenting on a possible flaw it has.

On such a website showing figures and analyzing in how far they are suitable for conveying information, one should stick to the rules of scientific publication.
Things to keep in mind:

Not criticize a persons work, but the work itself.
Formulate the criticism in a neutral way.

In a research paper you wouldn't say "the authors of ... [ref] were unable to produce sufficiently accurate results", but rather "Those results[ref] are accurate within the range of ....".
I would say the same holds true for showing the pictures. When creating this site always think about if it would go through a peer review process of a scientific journal.
Having a list of "bad pictures" would definitely not pass, but providing a model for some criterion and showing two examples, where one meets the criterion and the other does not, is perfectly fine and probably even useful.

There is only one thing I have an issue with in this answer which is the fact that a personal website or blog is just that, a personal page.  Why should a personal page be at the same level of a peer-reviewed work?  We do not use the same formalities we use in full emails or hand written letters when we use instant messaging or text messages.  Also, criticize in a neutral way?  I think we have all gone soft.

But you at least put thought into the answer, and put examples of what to say, upvoting for content....and the "bad pictures" part is spot on.   In my opinion of course.

I particularly liked the idea of providing desirable characteristics and using the examples to illustrate what "fits" and "do not fit" the criteria. I think this may be one of the ways to minimize harm without removing essence from the idea (e.g., showing that badly designed figures can get published but may be confusing).

@NZKshatriya I completely agree if it really was a personal website. But if that website clearly links to academic profile of the questioner, it is not personal anymore. As a scientist you carry a lot more responsibility in the surroundings of your research. So while you can still post any arbitrary junk on facebook about your last holiday, you cannot do that with opinions close to your research work.

If OP is simply discussing visualizations of data, and not actual research topics/projects, there really should be no issue.  But if he were to stray from that...  what i get from the questions wording is that OP wants to more or less do a correct vs incorrect type of page based upon his views on how data should be presented in visuals.  This can clearly be done without using anything tied to his current/former projects as far as the data is concerned.

@NZKshatriya Even if a Biologist created a personal website about some Archaeology I would expect this to meet certain criteria, or else I would be tempted to question his quality as a reseacher in Biology as well. So if the questioner wants to prevent that from happening, he could mind my opinion on the issue, given in the answer.

@NZKshatriya: "simply discussing visualizations of data, and not actual research topics/projects" - visualization of data is an actual research topic. "based upon his views on how data should be presented in visuals" - as far as I gathered, these views are probably tightly linked to research results about data visualization.

@NZKshatriya: As for "Why should a personal page be at the same level of a peer-reviewed work?" - reputation-wise, it is not. But in terms of diligence while writing, intended reliability and accuracy of the statements made, and neutrality in presentation, a personal research-topic-related page can certainly be seen at the same level of a peer-reviewed work - as well as of other non-peer-reviewed works such as project reports, publications for general audiences, topical overviews for book chapters, etc.

@O.R.Mapper Not exactly.  Take the way it was visualized, and plug in different values and variables.  I highly doubt that one copyright a mode of visual representation.

Yous should really ask yourself what do you gain here by using authentic data. I firmly believe you have every right to cite someones work and criticize what's wrong in it. But in context of a blog, what do you really gain from it?
You could just make models based on real life examples. And, if you want to keep the authenticity, every article can end up with:

Example in this article was inspired by real data in insert doi here

But in that case make sure you actually model your own example, copying and editing the data would certainly NOT be OK. At the same time, make sure the problem you illustrate is still the same as in the original.
Yeah, it really boils to gain vs possible loss. Even if you just get some pissed email, you'll have to ask if it was worth it for a blog article.

Pissed off email can be amusing.   they dislike what you say so much, that they are going to waste time they could spend being productive, in order to pay attention to you, the subject of their ire.   Ironic isn't it?

"Here's a bad graph that you could hypothetically make, let's fix it up" seems to me a far weaker statement than "Here's a real life bad example that was published, let's fix it up."

@Jeff This is why I suggested making fake example modeled by real example. Applying the abstract concepts learnt on the fake example to the real example is a nice exercise for the student.

David Zwicker already said it all in a comment. If you could include his comment I think this should be the accepted answer.

@Jeff The argument would probably go "All made-up examples are based on some bad real life cases. It really happened that way or in a very similar way. So let's fix it up."

As I would in any situation with moral ambiguity, I'd apply the golden rule: Do unto others as you would have others do unto you.
If you would not want others to do it you, then do not do it to others yourself.
On top of which, the fact that you're having moral qualms about it already highlights that it might be something you should avoid.
All this being said, I'm all for "teachable moments."
I would use a blanket "views expressed" disclaimer and keep it as professional as possible about the figures themselves, only.

Before we begin—a little disclaimer…   Any statements made, views
expressed, or opinions given represent my personal views and opinions
alone.   None of these statements, views, or opinions given by me
(nor any of the information appearing on these slides) are endorsed
by, nor do they necessarily reflect, the opinions of the University of
Alaska, UAA, nor any other colleges or organizations affiliated with
these institutions.
The Hidden Costs of Outsourcing: Why Alaska Needs its Own Law School, trwatts.

What do you think?

"Do unto others as you would have others do unto you." - this just doesn't work. I don't mind criticism, even harsh one. Following this rule, I almost lost some teeth.

"the fact that you're having moral qualms about it" - frankly, "Is there any moral (or even legal) problem in criticizing other people's figures on my website? Should I expect any sort of retaliation if I decide to do that?" reads to me like the OP rather has no moral qualms about it, and is thus asking the community whether anyone else could have any moral qualms that might cause retaliatory behaviour.

@O.R.Mapper. I see what you mean.

@TomasZato Heh, might it be possible that you are mixing up the golden rule with the other well-known-but-not-the-same-rule, "An eye for an eye, a tooth for a tooth"?

Personally, I don't see why morality is entering the argument as to blogging about dataviz figures (called it blogging, as that is what it is lol).    I wouldn't see Morality entering into something as basic as intellectual argument/discussion.   Now, warfare/right to die, things of that nature I can understand Morality being brought up.  Etiquette and Ethics I can see applying to blogs though lol.

Just noticed something.  This "answer" ends with a question.  Therefore this is not an answer is it?

@TeacherKSHuang Certainly not, because I do not remember assaulting anyone's teeth, so this doesn't qualify for tooth for a tooth case.

@TomasZato. I see. Then I'm not sure how you almost lost some teeth following this rule....

@TeacherKSHuang Well, it's all in the first comment. I criticized someone in a way that I'd personally not mind. That person did.

Ah, yeah, I see what you mean. I think you followed the rule, but from the wrong perspective. From the perspective of the person you criticized, the person probably felt, "I would not want to be criticized, so I will not criticize others. And I will take into account how others feel about being criticized, so I have even less reason to criticize."


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Trouble choosing an appropriate arXiv category for a paper
I am having trouble choosing a category for a paper to upload to the arXiv.
The paper gives some results concerning substochastic matrices, M-matrices, and algorithms to determine whether a matrix is an M-matrix.
I am having trouble choosing an appropriate arXiv category. Certainly, if there was a category for matrix analysis, it would undoubtedly be the right choice. There are a few possible approximations which I list below, along with some reasoning.

math.RA (Rings and Algebras): I often see papers concerning matrix analysis here (C^{n x n} is a ring, after all).
math.FA (Functional Analysis): Matrix analysis is certainly a subset of functional analysis, but I'm not sure if this feels quite in spirit with the category.
math.NA (Numerical Analysis): M-matrices appear frequently in the numerical analysis literature.
cs.DM (Discrete Mathematics): algorithms in the paper analyze and manipulate the adjacency digraph associated with a matrix.

If your paper contains non-algorithm results on digraphs as well, you might want to consider math.CO (for cross-posting) as well. The tag is huge and (to some extent) overused (I think it should be split, the sooner the better, into at least algebraic combinatorics and graph theory and maybe also infinitary combinatorics), but what you seem to be describing fits just as well inside it as many other things.

This question may be considered too specific for this site, but I'll try an answer anyway.
As someone who works in numerical linear algebra and has used M-matrices extensively, I think a submission with this topic would be welcome in math.NA. Math.RA would be my second choice, followed closely by Math.PR (probablity) which you haven't considered. One of the main results of your paper is an algorithm, and it must be an algorithm which is (at least partly) numerical in nature if it can recognize M-matrices. As you correctly note, M-matrices and algorithms involving them are a first-class citizen in numerical analysis, and they are featured in articles appearing in journals in the field. Even abstract properties of them would be on-topic, because their main use is (probably) going to be proving the properties of algorithms.
I must say that the arguments you list in favor of math.FA and math.RA seem quite vague to me; they would apply to almost all of numerical linear algebra. As for cs.DM, as I said earlier, your algorithm necessarily is not entirely discrete, so it seems less appropriate.
Anyway, you probably won't go wrong with any of NA, RA or PR. Arxiv's categories have some overlap. As Pieter Naaijkens's answer suggests, you may get slightly more visibility from the people in your field if you go for NA.

Thank you Federico (+1). I assume your choice of math.PR stem from the results on substochastic matrices, right?

@parsiad Yes (although I don't know how prominent they are in your paper).

I am the moderator for cs.DM.  I can't be sure without actually seeing your paper, of course, but it would probably be fine for cross-listing in cs.DM.
I wouldn't worry about the classification too much; pick a reasonable primary category, and then cross-list in a few categories where you have good reason to believe people will be interested.  If you cross-list in too many categories, your paper will get flagged, which will delay release until the mods can figure out which categories to discard.  But papers with two or three secondary categories are fairly common.
arXiv allows moderators to accept or reject papers into their category and to propose new categories, in both cases either as primary category or as a cross-list.  As a moderator, I see every submission for which either the author lists cs.DM as one of its categories, or an admin/moderator proposes cs.DM as a new category.  Occasionally preprints will appear under an entirely different set of categories from the ones the authors proposed.
The arXiv system also classifies each submitted paper by comparing the text to papers in every category; moderators and admins see an automatically generated list of suggested categories for their papers.  (I've included a censored snapshot of the moderator page for an unreleased submission below.)  So the moderators can propose categories that the authors might not have considered, even if the paper falls outside their area of expertise.

Note that it is possible to cross-list your paper in (a small number of) different categories, so if you believe your paper fits in multiple categories, this is the right thing to do.
Of course the question still remains: which categories to choose? Besides the content there are a few factors that you might want to consider. An obvious one is to try to see which category most people in your field choose. These are likeley the categories they pay the most attention to themselves, so this would ensure the greatest visibility along your target audience.
I am not very familiar with your field, but math.FA would be appropriate if your paper uses lots of analysis. Most papers there consider infinite dimensional spaces. Just becasue M-matrices are used in numerical analysis does not make math.NA automatically a good fit, and I would only cross-list there if the paper would have applications to numerical analysis. The other two from the looks of it sound more appropriate, but again this is not my field and it is difficult to judge without knowing the paper.

Thank you Pieter (+1). The only possible argument for math.FA is results on various operator norms, but since most of the arguments are combinatorial, perhaps this is not ideal, so I agree with you.

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Is it considered misconduct to omit a university that you were enrolled in, but didn't attend any classes at, on graduate application?
Is it considered an academic misconduct to skip listing a university's name in the graduate application, in which somebody got admission but never attended any class/lab/test/exam whatsoever and as a result his transcript is shown failed in all courses in one semester?

So, you "never attended," but you registered for classes and then blew them off?  In other words, you registered for classes and failed all of them through doing nothing?

Whether someone has performed "academic misconduct" is something that a specific body of people must decide upon using both general principles of academic ethics and the specific rules of the academic body in question. It depends at least a bit on who is doing the considering.  So it seems better to think in terms of whether certain actions could reasonably or likely be construed as academic misconduct by certain parties.
When it comes to graduate admission, the relevant academic parties are the admissions committee and the authorities (faculty, administration...) of the institution.  It depends a bit on what the application asks for.  If you are asked to supply all college/university level transcripts (a common request) and intentionally omit some, then certainly you are behaving dishonestly in the usual sense.  Whether the dishonesty will be construed as academic misconduct if discovered is up to the relevant academic parties to decide, but: yes, there is a real risk of that happening.
You make it sound like "somebody" got a bit of a raw deal by getting failing grades for classes that were never attended whatsoever.  If somebody never showed up at all, then it seems like there is a good case that the enrollment was some kind of misunderstanding and that grades should not have been given.  Somebody should seek to fix that with the institution that issued the failing transcript.  It will probably be at least a certain amount of fuss -- e.g. contacting every instructor to get them to confirm that the student was a pure no-show.  If somebody's best efforts do not suffice to resolve the question, the ethical thing to do -- and the path which nullifies any claims of academic misconduct -- is to include the transcript together with an explanation of what happened, possibly along with parties to contact for additional corroboration.

It is also relevant whether Somebody received financial aid for those classes, especially if any of it was paid in cash rather than e.g. as tuition reduction.

The question you need to answer here is: is this event relevant to your graduate application? There are several reasons why it might be:

The graduate admission process might for example somewhere in the fine print explicitly ask for all previous universities you attended. In that case, they decided it is relevant and you must mention it.
You might only be able to talk about what you did with your life that time period if you mention this university. Can you honestly talk about what you did that semester without mentioning this university? Did the admission to this university play a role in any academic and/or life choices you made during or after that time? If it is part of your (academic) life story, you need to talk about it.

One thing to keep in mind is that there might be records of your enrollment at this institution. If the admission committee finds you were enrolled there, but failed to mention it, that would be a major red flag. It might be worth mentioning this university and give your story, just to prevent taking this risk.

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What is the purpose of textbooks?
I as a student have done various courses at my university and for each of these courses a textbook was prescribed. On the other hand, the instructor provided his notes as well. The textbook was huge (approximately 500 pages) whereas the lecture notes were only 100 pages and really short and clean. During my studies, I rarely used the textbook but relied on the notes and I think that I just did fine. I am not the only student who rarely uses prescribed textbook but other students also think the same in my classes. The students that I talked to prefer notes mainly because

textbooks are expensive so not everyone can afford buying 5 textbooks each academic session (5 subjects per session) which makes it 10 textbooks per year and the average price for each textbook is $150;
textbooks are huge (about 500 pages) so students prefer to use notes which is clean, short, and summarized;
It is true that during an academic session, a student studies for a particular subject, but he may forget some of the material so he needs to study it again few days before the exam. Studying a 500 pages textbook few days before the exams is practically impossible given the stress and pressure that students face when they get near the exam.

The only benefit of the textbooks that I can tell is that if you find a particular concept unclear, you can look at the textbook for clarification but most students really do not do this. If they struggle with a particular concept, they go to the office hours of the instructor and ask for clarification. The textbooks also have many exercises so if any student needs to do more exercises, they can uses the prescribed textbook but I have not seen any student who does this.
What is the purpose of a prescribed textbook in a course taught by instructor and why do instructors emphasize reading it?

The other side of this question: What is the benefit of writing lecture notes for an introductory course vs using a textbook?

The textbook presumably contains more information than the lecture notes. Under this presumption, a student can learn more from a textbook than the lecture notes.

Lecture slides/notes, course notes, and textbooks simply provide different levels of abstraction of the (more or less) same underlying material. Which, when, and how you use them really depends on your use case.

The title is misleading. Your question is not about textbooks themselves, but rather about the use of textbooks in classes. By the way, as a student myself, I would like to attest to the fact that not only do I frequently use recommended textbooks to facilitate my learning (albeit, none are mandatory), but I actually enjoy using them. I find it very helpful to read other sources (not just the lecture notes) to get a variety of explanations of any one topic.

What I have often done is to ask the professor if I could use an older edition of the same book.  The answer has generally been "yes."

Maybe if you are just relying upon the lecture notes you are only "learning" for the tests and might not actually have a deeper understanding of the material at hand? I know there have been many classes where if I just studied the lecture notes I would do fine for the course but pretty much hamstrung myself for subsequent courses down the line. On that same note I also had classes where I did that and never needed the material again. I guess it really depends on what you will do with what you learn.

The question is based on several false premises and this also leads to an answer:

[…] students prefer to use notes which is[sic!] clean, short, and summarized

That's not true for many students. In fact, there are students who dislike summarized text and like textbook style.

It is true that during an academic session, a student studies for a particular subject, but he may forget some of the material so he needs to study it again few days before the exam. Studying a 500 pages textbook few days before the exams is practically impossible […]

Textbooks have a table of contents and often an index, so it is not at all impossible to brush up on a certain topic using a 500 pages textbook last minute (given that you know the context and some buzzwords).

[…] you can look at the textbook for clarification but most students really do not do this.

Many students do this, really.

If they struggle with a particular concept, they go to the office hours of the instructor and ask for clarification.

Some come to office hours, some don't. For my courses, only very little students come to office hours and most study by other means - presumably some read a textbook.

The textbooks also have many exercises so if any student needs to do more exercises, they can uses the prescribed textbook but I have not seen any student who does this.

Look harder. There are these students who do additional exercises.
Last point: Textbooks are used by professors to create their courses. There are great textbooks for introductory courses and professors do not want to reinvent the wheel (well, a worse wheel, actually). If they rely on textbooks for their preparation, why not tell the students which books they used?
I don't know if there are courses where you really have to purchase a textbook - you may just decide to not buy it and may be fine. I prefer to announce textbooks that are available online through subscriptions of my university and in the library as a paper copy (with at least one "permanent/reference copy" that can not be borrowed) so that the students can use the book for free.

I don't know if there are courses where you really have to purchase a textbook -- a number of courses I took at my undergrad used the textbook solely for homework assignments/problems. As a result, someone in the class had to buy a copy, even if only so everyone else could copy the questions from them. The problem becomes organizing who is buying the textbook in that case. I also had courses where professors stated we had to have the book -- only for them to use it once. IMO, that's the more major problem.

@tonysdg - There should be a copy of the textbook in the library's "reference" shelf behind the desk, for use in the library.

@aparente001: "Should be" and "is" are unfortunately two different verbs (saying it only from personal experience. I agree with you 100% otherwise).

@tonysdg - I would point out the missing textbook to the department.  I guess I have too strong a sense of justice.

@aparente001 - No, I think others just have too weak a sense of justice :)

@tonysdg - I remembered another trick.  See my comment above.

I think your [sic] is uncalled for. "which" here refers to using notes, not notes.

Sorry for the long answer, but the title of the question scares me, and brings visions of a world where few (nobody?) value textbooks anymore (the horror!). So I knew I had to jump in. This is my (a student's) perspective on why textbooks are important in a course.

textbooks are expensive [...]

As a computer science undergrad from India, I do sometimes feel a pinch in my pocket while purchasing particularly expensive textbooks. This rarely happens, however, since I view the money spent on textbooks as an investment for my education – much like the tuition fee for my university. Moreover, many authors (and sometimes universities) generously provide free PDF copies of textbooks online for personal use; for example Computer Vision, Deep Learning.

The textbook was huge (approximately 500 pages) whereas the lecture notes
  were only 100 pages and really short and clean.

There are a couple of very simple reasons for this. Firstly, A (good) textbook is written in a manner in which new material is introduced gently, giving background information and building the idea from the ground up which makes the concept seem simple and intuitive. For instance, in our course on compilers, we use the legendary Dragon Book, which when read judiciously builds up complex ideas from scratch in a manner that makes them seem trivial, when they are obviously not. (To appreciate this – if you have done computer programming before, and find it hard, consider how hard it must be to write a program that can correctly decode a general computer program to make the computer understand what to do).
Secondly, I don't know which course you study, but if it is something that can have a strong mathematical background (such as CS), then I doubt if your instructor's notes will do justice to the material in terms of elucidating the underlying proofs, analyses, etc. In a subject like CS where these aspects are crucial parts of the material, omitting them for the sake of simplicity doesn't seem like a good idea. The notes are an aid to learning, they are not a replacement for the textbook.

During my studies, I rarely used the textbook but relied on the notes
  and I think that I just did fine.

That is very common, unfortunately. Although I always read the textbooks for all classes I take (I love textbooks :D), I am often not among the top scorers in a course. My observation is that this is because most of the top-scoring students in a course do not study the material, they study for tests. They restrict themselves to instructor's notes and test questions from previous test papers to prepare themselves for tackling the test well. They do not spend time in building the ideas from basics, which is what textbooks are for.

textbooks are huge (about 500 pages) so students prefer to use notes
  which is clean, short, and summarized

As Dirk mentioned, that's not really true.

It is true that during an academic session, a student studies for a
  particular subject, but he may forget some of the material so he needs
  to study it again few days before the exam. Studying a 500 pages
  textbook few days before the exams is practically impossible [...]

As Dirk mentioned, it is not impossible to revise smartly from textbooks using the index, etc. But my personal opinion on this is that textbooks are sometimes not very efficient for revisions / studying for exams. For these, your own notes (made during lectures or while reading the textbook) or your instructor's notes can be a useful aid (not a replacement).

The only benefit of the textbooks that I can tell is that if you find
  a particular concept unclear, you can look at the textbook for
  clarification [...]

That is not the only benefit of textbooks! As I mentioned earlier, (good) textbooks provide context to the material, they are responsible for building ideas, not simply providing information. In my opinion, if you really want to understand and appreciate a subject, then this deep, contextual learning by building new ideas over old ones is an important journey – and an enjoyable and fulfilling one too!

If they struggle with a particular concept, they go to the office
  hours of the instructor and ask for clarification

Perhaps this is not a problem with you, but I (and many of my peers) have often suffered due to the lack of a qualified instructor for a subject. During such times, textbooks have been the guiding light for many students like us. It was during times like these when I realised the value of textbooks.
Finally, a good textbook is usually written by a person well experienced in the field, for the sole purpose of explaining the material to the reader. If you do have the opportunity to meet such an expert in person, who has the time, patience, and skill to frame his thoughts in a simple and coherent manner, then do go talk to him – but still save your textbooks because you can read them again and again over a period of years ;).

A personal experience from a math student:
Concepts, proofs and derivations in the lecture (notes) are written one way. Sometimes / Often this way is not understandable to you, so you look for a different approach, a different wording, a different start for a concept in order to understand it.
The examples in the lecture notes usually only cover the most common cases, but in the exercise sheets other cases are asked to be solved.
Now, these things can be found in textbooks. But nowadays many of these things can also be found online, i.e. Wikipedia or various forums. For the textbooks, as Dirk mentioned, some are available for free, online, if your university has a contract with the publisher, and there's always the library.
To answer your question: The purpose of a textbook is to provide you with a different perspective.

As an instructor, I'm often led to cringe by the price of textbooks. I often tell students pretty upfront that I understand if they opt not to purchase the textbook, but that they are doing so at their own risk. While I try to explain things clearly myself, I also tell students that the textbook has a slightly different - and often complementary - angle on most things (and different examples, and a useful glossary at the back, and interesting tangents for those interested). The students who both come to class and keep up with the reading are: a) getting more exposure to the material (spaced repetition reportedly being a very good thing for learning, though I'm far from an expert), and b) having things explained to them again in different terms, so more of it is likely to stick in the first place. Since most of my midterms and exams reward conceptual understanding more than memorization, it is to my students' advantage to work through my notes and the textbook while studying (as well as asking me questions, etc.).

As an instructor, I'm often led to cringe by the price of textbooks ... Me, too.  In the future, when you are in a position to choose a textbook for a course, find out the price first.  Some publishers (even big important publishers) attempt to hide the price from the prospective instructor...

textbooks are huge (about 500 pages) so students prefer to use notes
  which is clean, short, and summarized

There are several dangers to this - first, the clean, short, summarized notes don't have all the details, whereas a textbook might. Indeed, the notes may be missing essential details because they are in the textbook itself.
Additionally, and I've experienced this twice in my career, there is a benefit to having information from two different sources. If you don't understand someone's presentation of material during a lecture, it's possible you won't understand that same person's presentation in the notes. Having a textbook, written (often) in a different voice, may be exceedingly helpful.

It is true that during an academic session, a student studies for a
  particular subject, but he may forget some of the material so he needs
  to study it again few days before the exam. Studying a 500 pages
  textbook few days before the exams is practically impossible given the
  stress and pressure that students face when they get near the exam.

To be blunt, failing to leave time to study for an exam is a failure of the student, not the textbook. Additionally, said hypothetical student should only need to read some sections of the textbook - though which sections those are may vary by student.

The only benefit of the textbooks that I can tell is that if you find
  a particular concept unclear, you can look at the textbook for
  clarification but most students really do not do this.

[Citation Needed]
Also, I don't plan things for what "most students do". I plan for what a student should be able to do to fully engage with the course and material.

If they struggle with a particular concept, they go to the office
  hours of the instructor and ask for clarification.

And it's entirely possible the instructor will say "Chapter 3 covers this really well...". Or, as noted, that there may genuinely be a disconnect between how the instructor explains something and how the student understands it.

Another seasoned student here, coming from Germany.

The only benefit of the textbooks that I can tell is that if you find
  a particular concept unclear, you can look at the textbook for
  clarification but most students really do not do this.
  Well, I don't usually care about how other students do their work. In fact, compared to the average students, I'm quite quick in understanding things and often do so during the lecture, not by studying after. However, of course I too came across concepts I couldn't understand using my notes, and certain textbooks helped me overcoming my shortcomings.

As others mentioned already, you should also take into account who has written the book. Different authors have different styles. I could name (German) authors which I completely understand and some which have a terrible style of writing, for my taste.

The textbooks also have many exercises so if any student needs to do
  more exercises, they can uses the prescribed textbook but I have not
  seen any student who does this.
  Again, bad for them. Of course there are exercises which may be not easy to solve and not being statements that are much of interest, but by trying to solve them alone you can improve your understanding of the topic because you look up definitions etc.

The other answers have covered pretty anything else, but I would like to answer the title question directly (ignoring the "in lectures" part).

Textbooks are not for students only. When you specialize in a mathematical topic and you notice that for your research, some other topic may be of interest as well, before you speak to any colleague you will first provide yourself with the basics of the new topic from a textbook, to get the general idea.
Mathematics is a lot of fun and wonder. Once someone is intrigued with the beauty of mathematics, why not look up some math that is not covered in your courses? This way I learned about knot theory and topological vector spaces. Most students here will sadly never know about this stuff unless it is covered in a seminar they stumble into. (In fact, just today someone I know told me he is now in a course of chaos theory and then I asked what happens in this course :-) )
There are not only beginner's text books but also such that cover certain topics that were only discussed in papers previously. And believe me, collecting a bunch of relevant papers can be time consuming. So I was really happy I came across something called "Selected topics in Graph Theory".


text:
Matriculating as master's student just for credits, with the intention of dropping after a year
This is an unusual situation where I want to take classes and receive credit for my transcript at a particular university but I am not currently a student there.
At some point in the next few years I will applying for a program that I actually do plan to complete, either PhD or master's, but not until taking more classes at this university.
What are the considerations I should be aware of if I were to apply, be accepted, matriculate, etc and drop after an academic year, i.e. two semesters? I assume that if anything this would make it more difficult, from an 'ethical' standpoint, to be admitted to a program in the future if I were to explain my reasoning for having dropped out, but I'm not sure if it would be that important.
In particular, it will be clear that I matriculated and dropped in order to preserve continuity with my previous studies (just completed). i.e., it will be obvious to a program that I apply to in the future that I do not intend to matriculate and drop again as I would do here.
To clarify, I would not be transferring to another school, but dropping out entirely and recommencing my degree from scratch at another time, likely at least a year after dropping, but with the additional courses in my transcript.
EDIT:
I should also clarify that this university does not offer a 'non-degree' program so that is not an option.

Is there a reason why you don't start your target program as soon as possible?

Basically want to learn more before I get there, and there's a specific school I really want to go to. Want to be as well-prepared as possible.

From my experience, you might be better off applying to your target university directly. Do you see this as an option?

It's a STEM field where it's really beneficial the more knowledge you have. I want to be able to get to the point where I can do some interdisciplinary research (not necessarily 'purely' in my field), not necessarily officially as part of my degree but maybe as something that I move onto after it. In general your judgement would be that waiting too long looks bad?

I don't think that waiting looks bad, I think it just impedes your own learning. I've posted a complete answer.

I'm concerned that you are significantly overestimating the weight these classes would add to your Masters or PhD application.  For one, these applications can be quite different, especially in the US where direct PhD is an option.  PhD admission committees are ultimately looking for proven ability to do research, which additional classes will not demonstrate.  From their perspective, classwork is the 'easy' component, and lack of knowledge in certain areas can be supplemented after admission.  On the other hand, to start, then restart a MS seems like a waste of time and money to me.

You know you are planning to drop out, but no one else needs to know.  People's plans change all the time.  For example, a person might start a master's, then realize he actually wants to work toward a PhD.  He might start at one institution or in one program and realize he actually wants to be somewhere else.  If he has done good work before the change, and if he is not someone who habitually starts things but abandons them before finishing... I don't see a red admissions flag here.
I don't see an ethical problem either, because when you start a master's program, you are part of a flock.  The program doesn't suffer if you leave after 2 semesters, and an advisor hasn't invested a lot of time and thought into how to best guide you.
Caveat: I have never sat on an admissions committee.

Most, if not all master's programs in the US have a 5 year requirement. You must finish your degree within five years. You can certainly matriculate, take classes, and then drop out. Those class will be on a transcript which you can transfer elsewhere. However, graduate programs are specific to each school, meaning a class you took at University A, might not transfer to University B. The worst that can happen is that your classes don't transfer over and you will have to start from square 0, at which point the additional courses would be useless and all that money you spent would have been for nothing.

I think that Michael C.'s and aparente's answers were correct in that it's fine for you to matriculate, take courses and drop out. However, I want to address your question from a more general perspective.
Should I study anything else before going to the program I really want?
If I read you correctly, you want to amass more knowledge before you start your target program. I believe that immediately starting your target program is a better decision. I acknowledge that you might lack some knowledge to fully grasp the courses in your target program from day 1, but this very lack of knowledge will be a motivating and stimulating experience for you. In other words, if you start a program in a well-known field, you might get bored and lose motivation quite fast. If you start a program in a field you know not-so-well, you'll put more effort into studying, and the rate at which you amass knowledge will be a lot higher.
Secondly, starting in your target program immediately will allow you to make acquantainces and network with the people from the same program, which will also benefit your learning.
Finally, one of your concerns is

[I want] to be as well-prepared as possible.

You are not the one to assess it. When you assess yourself, it's very easy to err on either side. The correct tool to assess yourself is the admission process: if you are selected to matriculate, you are ready for the program. This is why you should apply to the target program, at least to see if you get admitted.

Thank you for your advice. My specific situation I think warrants waiting a bit but I don't really want to get too specific.


text:
Is it possible for a PhD student to survive in the USA only on TA/RA money?
Suppose, a prospective PhD student doesn't have money to self-finance his PhD in the USA.
Is it possible for a PhD student to survive in the USA only on TA/RA money?

Yes, if you are frugal (e.g. go for shared housing).  There probably won't be money left over for travel.

@BenCrowell: How does the loan thing work if you subsequently get denied a visa to come here and pay it back? Does it completely ruin your credit history for the future unless you find a way to pay it back from outside the country?

@Mehrdad: Sorry, I changed the comment you were responding to into an answer. I don't even know whether international students have access to such loans. I would guess that they do not.

@BenCrowell: Oh I see, okay.

@Mehrdad foreign students aren't eligible for financial aid (including federal student loans) under Title IV of the Higher Education act.  It's unlikely that any private lender would be willing to make a loan to a foreign student.  For foreign graduate students in the US, financial aid means teaching/research assistantships and possibly institutional fellowships or some kind of scholarship from your home country.

Also keep in mind that foreign students can't work "an extra job" to earn more money.  Student visas allow only limited on-campus employment.

@Brian: This is generally true, but there are - or at least used to be - exceptions for international graduate students at Business and Law Schools (in terms of possible access to loans).

It was a while ago, but I was able to live (frugally) on my GA stipend. Lots of cheap housing and food was actually cheaper in the US, so yes, it's possible. You haven't mentioned whether you have to show proof that you can support yourself when you first arrive (I believe it was 20K US when I was a student), which should also help with the initial costs of moving. Is there still that requirement?

Although they seem a bit old, but I think it is worth mentioning this article and this one

@BrianBorchers For international graduate students, on-campus employment often isn't a option, as the research work is declared as 20 hours per week, which is the F1-visa limit. Some universities are nicer and declare fewer than 20 hours though.

To "survive": yes, many students do so, and typically without long-term ill effects. On the other hand, that TA/RA money is usually below the poverty line....

Do you have a family? The situation is very different if you are supporting yourself or a family.

@enderland, I have a family. But, its not a must to take them with me.

Agnostic of institution, each of which has its own set of policies governing TA/RA pay (more or less depending on the institution), a short answer is yes.  There are also, of course, different costs of living depending on where your institution is located (e.g., the cost of living in New York is much higher than in, say, the midwest). In any case, you will be paid a livable wage, but don't expect to be living any sort of lavish lifestyle.
Personal experience: I've been living off of TA/RA pay for the past 3 years. The pay offered by the R1 institution I attend and work for is located in the Midwest and, relative to other schools in our conference, offers one of the best stipends. As such, I've had enough money to not only live, but support my hobbies and enjoy a [non-extravagent] leisurely life during my non-working, non-academic hours (of which there are not usually a ton haha).

Pretty sure some people have to take out loans. Not sure if I call it a living wage if it doesn't cover basic living...

Sometimes student loans also cover housing, which can cover board. This certainly frees up other resources while enrolled in classes, but offloads a lot of burden onto your post-graduation years. I would imagine planning forward would also be part of the figure of "living on TA money", as you would be predominantly living off of loan money.

This is completely off topic, but could you explain your use of the word conference here? You appear to be using it as a synonym of region or perhaps field and I've never come across this usage before. Is it common in the Midwest?

@terdon The poster is referencing the athletic conference to which his school belongs.  This is relevant because, usually, all of the members of a given athletic conference have similar profiles.

"to which his school belongs": I think this is an example of our unconscious biases, as I see no evidence as to the poster's gender.

@terdon, Jacob Bond Yes, exactly-- I'm referring to athletic conference!

@Greg Martin I am a male. And will leave it at that -- this post is about grad stident wages being liveable, not about gender biases and pronouns, etc.

Thanks, I guess that's some sort of US thing. I'd never heard of it before.

@terdon Yeah, I was using the term quite ambiguously! Thanks for asking for clarification on what was meant!

@Mehrdad Yes, some do. What is liveable is somewhat person dependent. Some can live off a little, some feel they need a lot, so it's a bit relativistic. I think for the most part loans aren't necessary. Taking them out may be more respective of life style customs as opposed to definitive needs, but that is based on my opinions and observations (i.e., citations needed haha).

As both a native of New York City and an alum of a City University of New York school, I did not know any PhD students who were able to live on solely what the school offered. And the ones I knew were not living well. It possibly could have been done, I wasn’t particularly familiar with their finances, but at the very least no one was trying to do so, despite enormous demands on their time and willingness to accept rather-poor living conditions.

@DMML: Pretty sure your opinion about loans being unnecessary is wrong. If you're a STEM guy that's probably why. Go talk to some non-STEM students living in more-expensive cities and then you'll see.

@Mehrdad I disagree. I added sufficient modifiers that accommodate there being instances in which loans may be needed. However, I don't believe that this is "the usual", but rather the exception. I think you're absolutely right though re: non-STEM students living in higher cost-of-living cities. At my institution, however, graduate student stipends have been mandated as being uniform across discipline and program: I am paid the same as non-STEM students.  Again, I realize this isn't the case everywhere and thank you for your time in bringing up these important caveats on my original post.

The answer is usually yes, but it varies, and some people need to take out loans or get financial help from their families. For example, the graduate students' union at Yale is organizing around issues such as inequities in pay, lack of access to affordable childcare, and general difficulties in making ends meet when living in New Haven. http://www.nhregister.com/general-news/20170125/yale-university-graduate-students-in-9-departments-given-right-to-hold-union-elections
Students in the humanities are often less generously supported than those in the sciences, even at the same university. Fields that attract federal grant money do better than those that don't.
Think carefully about decisions such as your type of housing and whether to sell a car that you own before you start school. If you have more than one school to choose from, check carefully for differences in the local cost of living, which can easily be a factor of two or more between a small college town and a city like San Francisco or New York. In cities such as San Francisco with very high rents, make sure you have an affordable option for housing, such as on-campus housing or a subsidized university-owned apartment.
Health care is not free in the US, and although schools will usually provide health care to PhD students, there may be costs that are passed on to the student. Coverage may not include things that are included in other countries' national health services, such as birth control, drugs, and mental health care.

Health care coverage will also not cover a student's spouse or children, if any (I remember that as being a big point of emphasis/surprise in a document from the Chinese government on studying in the U.S.)

@anonymous: I doubt this is the venue for discussions of individual universities. Try their website directly.

This question is relatively vague, in that the US is a big place and remuneration for RA/TA positions is not equivalent across institutions.
However, I believe that the answer should explicitly address that the cost of living in the US varies considerably across the country.
Can a single person survive on the income provided by a typical stipend in the Midwest United States or the South? Yes.
Can a single person survive on the income provided by a typical stipend in the West or East Coast? Probably not.
Anecdotally, I have survived wonderfully in Indiana on a typical stipend. Upon moving to Boulder, Colorado for a PhD however, that stipend (same dollar amount) is not enough to pay for the basic living expenses and I have had to work an additional job to make ends meet.

Although TA/RA stipends vary somewhat between institutions, the cost of living can vary much more, even within a major metropolitan area like LA or NYC.  You might have to commute for an hour or more each way between a place where you can afford to live and campus.

How about University of Massachusetts Boston?

@anonymous UMass Boston you can live fine. You won't be able to afford to buy a beer in a bar, but you can eat from Market Basket and afford to pay rent and go to parties at friends houses.

I know a bunch of single people who got on their stipends in big markets (Chicago, Boston, San Fransisco bay area), but they did it my making compromises: share apartments, longer-than-ideal commutes, public transportation and so on. But they are in the same (federal grant drawing) physical science I'm in.

TL;DR: Yes - but this may often require you (and us) to fight for this collectively.
This question sheds light on the outrageous exploitation of junior researchers and teachers at universities in the US. A PhD candidate - and I mean the kind who does research and teaching throughout the week on campus, helps his/her research group and/or advisor with various projects and tasks, and is generally at the disposal of the advisor, research group, department or university - is a full-time employee. And not just any employee, but a skilled and meritotious one, which outside of academia would be gainfully employed. (Of course, salaries and job opportunities differ greatly between, say, an Electrical Engineering graduate and a graduate of a Semitic Language Philology, but still). Even if their work as PhD candidates also has the aim of earning a degree, that does not detract from their benefit to their employers: Universities are institutes which spread knowledge by teaching and ehnance knowledge and understanding by research, and PhD candidates promote these ends, devoting some of the best and most productive years of their lives. For this reason it is just and proper that they be paid a good salary.
Instead, what we (or rather, you; I work in the Netherlands where things are much better in that respect) have is a system in which many PhD candidates (and, again, I'm talking about the kind I described above) are not paid salaries at all, or are paid meager 'stipends', or paid for just their teaching / just their research, as though they work a small fraction of a full position, which is oviously not the case.
It is utterly infuriating that PhD candidates should worry about "surviving" their PhDs financially, rather than asking "Will I be able to put a down payment on an apartment or a house with my salary?". And let's not get started on how employers in the US and elsewhere used the entrance of women into the workforce over the last 50 years to increase downward pressure on wages so that if a couple wants to have children they have to choose between holding two jobs or near-poverty (and PhD candidates are very typically in that age range).
So, while for some (many?) universities, the RA/TA salary is enough to get by, it's almost universally much much lower than it should be (either the salary itself or the FTE fraction at which you're employed, or both). Occasionally you can sort of maneuver yourself into better wages by leaning on your advisor or obtaining some external source of funding for your research group; but that's the exception.
The rule is that without graduate researchers and teachers organizing in unions, without resolute industrial action, and without solidarity from older/tenured researchers and teachers - the answer to your question would be "no". So I urge you to join one or participate in forming one. I have (although, again, not in the US). You may not get all you want - but with Herculean effort, a measure of personal sacrifice and a bit of luck you might get some of what you need; and it won't be just you personally, but rather everyone at your university. So go to it; it is probably no less important than your actual research work.
By the way, there's recently been a landmark NLRB ruling buttressing the legal right to collective bargaining of graduate student-employees, in NLRB case 02-RC-143012 (The Trustees of Columbia University and Graduate Workers of Columbia, UAW; main decision here).

I think that "helps his research group" betrays our unconscious gender biases. PhD candidates don't have to be male. I do agree with your main theme that collective bargaining should be supported.

@GregMartin: You're absolutely right, changed it. And in my experience it's the female PhD candidates who have less family backing, and who are more likely to have to rely on loans. And who are more likely to have a lower salary/stipend.

As others have said, cost of living can vary considerably from one city (and region) to another. I think this deserves a very concrete comparison as it is important not to just have a vague understanding that the costs in one place might be more than another.
Let's start with Champaign, Illinois (home of the University of Illinois's flagship campus, a top research university) which is very much a "college town"—the metro area has a little more than 200,000 residents and a large portion of them are connected to the university. This is the type of place that, all else being equal, would be among the most realistic types of locations for there to be both a PhD program of repute and a cheap cost of living.
Now let's compare that with living in New York City, home of many research institutions and other colleges. According to Sperling's Best Places, the cost of living in New York City is twice as high as Champaign. And maybe more important, the cost of housing in New York City is over three times as high as Champaign.
I have lived in neither location, but have visited them when considering under- and post-graduate programs. PhD students in a social sciences field that I met in Champaign sometimes shared housing, but many of them shared houses (1500+ sq. ft.) in which each person had their own bedroom and usually there were multiple bathrooms. They were also usually quite close to the campus, though for some people/situations not walkable (for some, a walk that takes 20-30 minutes is unfathomable). In a place like New York, it's more likely you find yourself splitting a rather small apartment for similar or larger costs. For some, this is not a big factor...but for others, the ease of getting around, having one's own personal space, etc. are immensely important for their emotional wellbeing. More than one person I met in that program ended up even purchasing a home during their time there, though in both cases they were in a student-student marriage.
Another major consideration: Summer pay
Universities, disciplines, and departments all vary in their ability to fund graduate students through the summer months. There are basically three tiers:

No pay over the summer or any expectation thereof
Pay over the summer is competitive and/or awarded based on seniority, not usually or always available to early-stage grad students
Summer work is guaranteed or close to it

I will say that it is not always easy or straightforward to find summer work that even rises as high as a grad student stipend. More important is that most employers aren't dying to have an employee who will be leaving in 2 or 3 months. International students are also generally not permitted to work and may either need to go home or maintain a savings to get through the summer.
I have also been in a situation in which summer pay was the norm, but the pay was different/less. We were hired as lecturers or lab assistants rather than graduate assistants, placing us on a different payscale and under different hiring rules. We earned roughly 10-15% less in gross pay and the net pay was roughly equivalent (no student fees paid over the summer, but we were required to pay into a public pension program).
Speaking of,
Look into student fees and health insurance
Many graduate programs cover a large portion of health insurance premiums, perhaps sometimes all of the premium. This is a major expense to reckon with, so be sure you know how it works. When a program tells you how much they are paying, the number you get will be how much you get before various costs are taken out, including your health insurance premium. At my institution, 85% was covered and I paid somewhere between $25-$45/month for the premiums (spread across only 9 paychecks).
Another "gotcha" can be student fees and associated costs paid to the university. While tuition is customarily waived, many universities will still require graduate students to pay "student fees." At my institution, the supposed purpose of these fees included things like a public transportation pass, access to the fitness facilities, and some other "activity fee" kinds of things. Over the course of the year, I usually spent about $1000 on this and it is not optional. It was taken out of my paycheck post-tax, if I recall correctly. This isn't always going to be the case—both the requirement to pay fees and the amount—but you should be asking questions when figuring out if the costs will add up. If you drive to campus, you will probably need to pay for parking.
Can you live on stipends alone in the US?
To answer the question directly, the answer is "under the right circumstances." If the balance of the program's compensation, the cost of living, the auxiliary costs/benefits, and your own wants and needs sync up, then it will work. And I think there are many people who can have that balance work out, though it is probably not nearly a majority of graduate students.
I will note that my operating assumption is that living "only" on stipend money means that the person is not using student loans to pay some of the expenses.

How about University of Massachusetts Boston?

I can specifically comment on your choices. I'm currently in NYC and I have a friend that lived in Urbana. We both got the same salary/grant from the same sponsor. He lived like a king in walking distance of the university. I share a kitchen, my bathroom has less than 1.5m2, and I'm ~ 5 train stops away... I have one student coming to NYC with a budget of 1800USD/month, I already warned him that it is going to be tight!


text:
Parameter quantifying the number of publications expected from a good researcher
Is there any such notion of parameter that quantifies the number of journal articles someone has to publish to be a good researcher or to obtain his tenure?
For instance, how many publications per year is considered to be a good performance

for a PhD student
for a non-tenured university teacher

in computer science?

It'll be good if someone from HKUST can comment.  I heard that they prescribe a fixed number of journals to go from Assistant to Associate to Full Professor.

If you are in CS, isn't the norm conferences?  Shouldn't it be how many top-tier conference papers you have?

In Europe, institutions are currently more interested in the Impact Factor (IF) than in the amount of publications.

You could also check for the h-Index.

This depends dramatically on the subfield, even within computer science.

Note: I wrote this to answer the original question, which was less specific.
There's no a general answer to this question, because things change a lot by field.
If you want to have an idea of the extreme variability, you can look at this crazy table which reports the Italian minimum requirements to become tenured associate (II fascia) or full professor (I fascia), divided by field.
The third and the sixth columns of the linked tables report the minimum number of journal papers that should have been published in, respectively, the last ten and five years to be able to apply for the two positions. Then there are the number of citations and the h-index.
For instance, someone wanting to apply for a full professor position in mathematical logic is required to have at least 4 papers in the last 10 years, whereas an experimental particle physicist is required to have at least 164 publications if the average number of coauthors is between 501 and 1200.

Is there no notion of quality of the work, as measured for instance by the number of citations or one of the metrics that bibliometricians love to use?

@ZeroTheHero Yes, there is. The fourth column of the tables gives the minimum number of citations and the fifth is the (an) h-index. The minimum values are calculated as the medians (up to a certain year) of the parameters of the associate or full professors belonging to a certain field, at present.

thanks!  (My Italian is a bit rusty.)  Are these "hard" numbers or are they interpreted more as guidelines?

Wow!!!!!  I definitely learned something today.  Thanks and be well.

@ZeroTheHero Sorry I hit "enter" before finishing. They are hard numbers. The process is better explained in this answer from Federico. If you reach those numbers you can get the abilitazione (qualification). Once you get it, you're not yet associate or full professor until a university hires you in that position, you're just qualified to be.

I won't tell you what most of us think of this process ;-)

I can guess, but I also have many Italian colleagues so I can get ringside comments.

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text:
How to calculate value of a masters?
I have done Computer Systems engineering and working for a good company. I am interested in doing a masters (not really because I have much interest in theory but because it helps in career advancement.) How do I calculate how a masters will be a good decision and worth the time, money and energy? My goal is to become a Chief Technology Officer in 10 years (I have 3 years of experience right now and 1 year of experience after graduation.)

I doubt it is a good question for Academia if you are not interested in research.

I'm voting to close this question as off-topic because it is not a question about Academia but rather a question about career development

If your goal is to be a CTO (i.e. more business oriented) then the value of an MBA would be an idea worth considering. Once you reach a certain level of experience, education becomes icing on the cake. So in ten years time, if it came down between you and another candidate for a CTO position, and you had an MBA (or another master's degree), you would more than likely get the job.

You should evaluate:
a) the knowledge you will again doing the master: probably none, usually it is better to spend the time in self-study.
b) the legal rights the master gives you: in some countries, law request some levels or masters for some jobs or actions (in my country, by example, they are mandatory for teaching at high-school).
c) the prestige of the university.
d) the social contacts you will gain during the master: not only other students, good master has a lot of vip speakers.
e) if the masters includes practices (or research) done in external organizations, and if you are interested on these.

What the other answer failed to note that getting to a CTO position after only 10 years of experience is very rare indeed. Yes, there may be occasional persons that are capable of this achievement, but don't expect it to work for you. Seriously, you should reconsider your career goals if your goal is as ambitious as it is currently.
I would expect most CTO's to have master's degree. Some do have doctoral degrees, but it isn't so common that a doctoral degree would be a surefire way to get to the position. Typically, the benefit of a master's degree is worth more than the costs, so go ahead and finish (or start) your master's degree! For doctoral degree, I wouldn't recommend the same unless you are genuinely interested about the subject (I'm a doctoral student, but then again I'm genuinely interested about the subject).
However, what matters most is that you have to do your job very well to get to the CTO position. Write a lot of very good code, and be helpful to others when they ask questions about your code. If you're the person people ask questions from, promotion to a higher position may very well be near.

A CTO is basically a business manager. You won't be writing code. If you want to be CTO for a software company, become strong in Agile, and the SDLC. You should strengthen project management skills. To become a CTO in 10 years is pretty ambitious. You'll be working 16 hours a day every day for the next 10 years to meet that goal, so you won't have time to do a masters.