Why Primary Commodities Have a Lower PES than Manufactured Goods
Definition
Price Elasticity of Supply
A measure of the responsiveness of quantity supplied when there is a change in price.
The price elasticity of supply of primary commodities is generally lower than that of manufactured products.
Two things drive the gap: the time producers need to change output, and whether they can store what they make.
Long Production Lags Lock Output in Place
Crops must be planted and grown across a season, and minerals must be explored, drilled, and extracted over years, so output cannot rise until that process finishes.
A primary producer cannot lift supply quickly when the price goes up, so supply is price inelastic in the short run.
Limited spare capacity makes this worse: a farmer has only so much land and a mine only so many shafts, so there is little slack when a higher price makes extra output worthwhile.
As the time horizon lengthens, producers invest in more land, technology, and better practices, so supply becomes more elastic in the long run.
Storage Keeps Manufactured Supply Flexible
Many primary commodities are perishable, because food spoils fast, so producers cannot hold stock back and release it when prices rise.
Manufactured goods are usually easier to store, so firms build inventory and sell more the moment the price climbs, which keeps their supply comparatively elastic.
Example
Wheat takes a full growing season, so a mid-season price spike cannot pull more grain out of the ground.
Oil and mineral projects need years of investment before a barrel or tonne reaches the market.
A phone factory can add a shift or run its machines harder within days to meet a higher price.
Over a long enough horizon both kinds of producer can expand, so supply for each becomes more elastic.
Low Short-Run PES Makes Commodity Prices Swing
When output cannot adjust quickly, a demand change or supply shock forces most of the adjustment onto price rather than quantity.
So producers of wheat, oil, and metals face far more volatile revenues than manufacturers do.
In 2022, when Russia's invasion of Ukraine cut world wheat exports and prices spiked, farmers elsewhere could not grow more grain mid-season, so global supply barely responded until the next planting cycle, while a carmaker facing a similar jump could add shifts within weeks.
Over the long run supply becomes more elastic and prices settle, so the volatility is largely a short-run problem.
Reading the Gap on One Diagram
Put the two supply curves on the same axes so their slopes can be compared directly.
The steep primary-commodity curve barely moves in quantity for a given price rise, while the flatter manufactured-goods curve responds strongly.
That larger change in quantity supplied for the same price rise is exactly what a higher PES means.
Active recall
Why is the PES of primary commodities generally lower than that of manufactured goods?
How do long production lags and limited spare capacity keep primary supply inelastic in the short run?
Why does the ability to store output raise the PES of manufactured goods?
What happens to the PES of both kinds of good as the time horizon lengthens?
