Looking for Pinyin standards I have noticed discrepancies in how native Mandarin speakers spell certain words in Pinyin reflecting differences in pronunciation, for instance, pángbiān vs. pángbian and zǎoshang vs. zǎoshàng. I've been told that these reflect differences across dialects. I even find these discrepancies across dictionaries, so I'm wondering if anyone knows of a source for standard Pinyin spellings.
Note that sometimes the transcription reflects the actual reading rather than the "single-character-pinyin".

For example, 你好 is sometimes transcribed as ní hăo, even if the "actual" transcription per-character would actually be nǐ hăo. This happens because when two third tones are next to each other, the first one becomes a second tone (when reading/pronouncing the characters, not when writing). 

In other cases there is a totall loss of the tone, such as in 窗户 (window) transcribed — and read — as chuāng hu1, rather than chuāng hù.



1: The source is the CEDICT dictionary.