<p>In this demand curve, $a=6$ means that the autonomous demand for this good is of 6 units. That is, if the market price of that good was $0$, then people would demand 6 units. </p>

<p>It is reasonable to think that a positive income shock, or a shift in preferences making this good more desirable would make $a$ higher. I don't think there's any deeper meaning here, just that a downward sloping demand curve requires a positive intercept or else quantity demanded would be negative at any price $P$.</p>

CC BY-SA 4.0
2018-09-13T22:11:35.903Z
2018-09-13T22:11:35.903Z
Pedro Cavalcante
<p>I've been reading (trying to brush up on my economics knowledge) and came across the equation: $q_D = a + b(P)$.  The variable $a$ is explained as "factors other than price affecting demand."</p>

<p>I read up on non-price determinants of demand (e.g. income changes, preference changes, etc); but, what I've not been able to satisfactorily understand is how $a$ is calculated from those determinants.  </p>

<p>So in the equation: $q_D = 6 - 0.5(P)$, what does $6$ represent and how was it determined?</p>

<microeconomics><supply-and-demand>
Demand Curve Equation Explanation
Robert S
# Demand Curve Equation Explanation

(Asked by: username_0 on 2018-09-13)

I've been reading (trying to brush up on my economics knowledge) and came across the equation: $q\_D = a + b(P)$. The variable $a$ is explained as "factors other than price affecting demand."

I read up on non-price determinants of demand (e.g. income changes, preference changes, etc); but, what I've not been able to satisfactorily understand is how $a$ is calculated from those determinants.

So in the equation: $q\_D = 6 - 0.5(P)$, what does $6$ represent and how was it determined?

**Tags:** microeconomics, supply-and-demand

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## 1 answers

### Answer by username_1 on 2018-09-13. Score: 3 | Accepted answer

In this demand curve, $a=6$ means that the autonomous demand for this good is of 6 units. That is, if the market price of that good was $0$, then people would demand 6 units.

It is reasonable to think that a positive income shock, or a shift in preferences making this good more desirable would make $a$ higher. I don't think there's any deeper meaning here, just that a downward sloping demand curve requires a positive intercept or else quantity demanded would be negative at any price $P$.


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