<p>Price elasticity of supply is: <span class="math-container">$\frac{dQ_s}{dp}\frac{p}{Q_s}$</span>. Because supply slopes upward <span class="math-container">$\frac{dQ_s}{dp}&gt;0$</span>. <span class="math-container">$Q_s$</span> and <span class="math-container">$p$</span> are also positive so    <span class="math-container">$\frac{dQ_s}{dp}\frac{p}{Q_s}&gt;0$</span>.</p>

CC BY-SA 4.0
2020-12-10T00:51:49.413Z
May I ask: what is the purpose of the second ratio shown in the first and last sets. I'm referring to the p/q. Isn't elasticity simply dQ/dp?
StatsScared
CC BY-SA 4.0
2020-12-15T18:55:11.680Z
@StatsScared no the elasticity is by definition $\frac{dQ_s/Q_s}{dp/p}$ as it is relative change in quantity over relative change in price but that can be rearranged to nicer looking formula: $\frac{dQ_s}{dp}\frac{p}{Q_s}$
WilliamT
CC BY-SA 4.0
2020-12-08T11:18:48.043Z
2020-12-08T11:18:48.043Z
WilliamT
<p>What confuses me in particular is that I always thought of the concept of ‘elasticity’ <em>with respect to something</em>. That is, supply of x can be elastic with respect to y.</p>
<p>Am I missing something?</p>

CC BY-SA 4.0
2020-12-08T02:55:30.793Z
In context of supply or demand, elasticity generally refers to *price* elasticity. So the statement is actually supposed to be: "price elasticity of supply is positive". So as price increases, quantity supplied increases.
Dayne
<microeconomics><elasticity>
What does the following mean: "supply has positive elasticity”?
StatsScared
# What does the following mean: "supply has positive elasticity”?

(Asked by: username_0 on 2020-12-08)

What confuses me in particular is that I always thought of the concept of ‘elasticity’ *with respect to something*. That is, supply of x can be elastic with respect to y.

Am I missing something?

**Tags:** microeconomics, elasticity

> **Comments:**
> **username_1**: In context of supply or demand, elasticity generally refers to *price* elasticity. So the statement is actually supposed to be: "price elasticity of supply is positive". So as price increases, quantity supplied increases.  

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## 1 answers

### Answer by username_2 on 2020-12-08. Score: 2 | Accepted answer

Price elasticity of supply is: $\frac{dQ\_s}{dp}\frac{p}{Q\_s}$. Because supply slopes upward $\frac{dQ\_s}{dp}>0$. $Q\_s$ and $p$ are also positive so $\frac{dQ\_s}{dp}\frac{p}{Q\_s}>0$.

> **Comments:**
> **username_0**: May I ask: what is the purpose of the second ratio shown in the first and last sets. I'm referring to the p/q. Isn't elasticity simply dQ/dp?  
> **username_2**: @username_0 no the elasticity is by definition $\frac{dQ_s/Q_s}{dp/p}$ as it is relative change in quantity over relative change in price but that can be rearranged to nicer looking formula: $\frac{dQ_s}{dp}\frac{p}{Q_s}$  

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