高階ECON-ELAS-021
Why is price elasticity of supply usually lower in a short period than in a long period?
A. Some inputs are fixed in the short run, so output cannot change as freely.✓ 答案
B. The law of demand is stronger in the short run.
C. Firms always face perfectly elastic demand in the long run.
D. Supply elasticity is calculated from income, which changes slowly.
解說
PES measures how quantity supplied responds to price. With fixed plant or contracts, firms cannot expand much at once, so short-run PES is lower. This is not the law of demand, and it is not an income elasticity.