Oct 30 2009
Calculating the price elasticity of supply of natural gas
Previously I blogged about the decline in demand for natural gas and the resulting decrease in quantity supplied by gas producers:
Welker’s Wikinomics Blog ’Disequilibrium in the market for natural gas
Professor John Whitehead over at Environmental Economics Blog took the liberty of calculating the price elasticity of supply (PES: a measure of the responsiveness of producers to a change in a product’s price) of natural gas. In this case, since the price of natural gas went down, producers decreased the quantity of gas supplied. Professor Whitehead simply found the price of natural gas, and the rest was easy, given the date from the original article:
“Amid an abundance of natural-gas supplies and soft prices, gas producers are starting to pull the plug. Chesapeake Energy Corp. said it will cut 6% of its gas production in September in response to low natural-gas prices.”
And the professor’s calculation of PES:
PES = (change in Q/Q)/(change in P/P)And the percentage change in quantity is 6% (“Chesapeake Energy Corp. said it will cut 6% of its gas production …”).
…natural gas is about $5.75. During the period Feb-July ‘07 price was pretty stable at about $7.50.
So, change in P/P = (7.5-5.75)/5.75 = .30 or 30%
Therefore: PES = 6/30 = .2
Update: While going over this blog post with my AP Econ students today, we noticed that the calculations from professor Whitehead’s blog are actually incorrect. The PES for natural gas is NOT 0.2, as Whitehead showed. Here’s why:
The original price of NG was $7.50, and when the price fell to $5.75 the quantity produced by Chesapeake Energy fell by 6%. Whitehead’s calculations of the percent change in price are wrong because he divides the change in price by the new price, when he should have divided it by the original price. The numerator in the PES formula should be (5.75-7.5)/7.5, which comes out to -2.33.
The PES is therefore -6%/-23.3%, or 0.26
While supply is still inelastic, it’s not QUITE as inelastic as professor Whitehead’s blog indicated.
Discussion Questions:
- With a price elasticity of supply of 0.26, how would you describe the responsiveness of gas producers to changes in price?
- Do you think the PES for natural gas would remain 0.26 over time if the prices were to remain low? Why or why not?
- What is the primary determinants of PES?
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pply curve, downward sloping demand curve), the consequences of a change the price of a currency (the exchange rate) is far more powerful than a change in the price of a particular good or service in a product market.


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