Elasticity of supply

1) Calculate % change in Qs = (change in Qs ÷ original Qs) × 100. 2) Calculate % change in P = (change in P ÷ original P) × 100. 3) Divide: PES = %ΔQs ÷ %ΔP. 4) Interpret: >1 = elastic, <1 = inelastic.

Flatter supply curve → more elastic (producers respond a lot to price changes). Steeper supply curve → more inelastic (producers cannot easily adjust output). Vertical → perfectly inelastic. Horizontal → perfectly elastic.

A measure of the responsiveness of quantity supplied to a change in the price of a good. PES = % change in quantity supplied ÷ % change in price.

%ΔQs = (200/1000) × 100 = 20%. %ΔP = (50/200) × 100 = 25%. PES = 20%/25% = 0.8. Supply is inelastic (PES < 1) — producers cannot fully match the price increase with extra output.

Because of the law of supply — when price rises, quantity supplied also rises (and vice versa). Both the numerator and denominator move in the same direction, giving a positive ratio. Unlike PED, you do not need to worry about signs.

Mostly quantity rises with only a small price increase. Because supply is elastic, producers can easily ramp up output to meet the new demand, so there is little upward pressure on price.

Show each step: (1) % change in Qs with working, (2) % change in P with working, (3) PES = answer with division shown, (4) interpretation — state whether supply is elastic or inelastic AND explain what that means in context.

Mostly price rises with only a small quantity increase. Producers cannot easily increase output, so the extra demand mainly pushes up the price rather than increasing the quantity traded.

PES > 1 → elastic supply (Qs changes more than P — producers respond quickly). PES < 1 → inelastic supply (Qs changes less than P — producers struggle to respond). PES = 0 → perfectly inelastic (vertical S). PES = ∞ → perfectly elastic (horizontal S).

The structure is identical (%ΔQ ÷ %ΔP), but PES uses quantity SUPPLIED while PED uses quantity DEMANDED. PES is always positive (law of supply); PED is usually negative (law of demand). Both measure responsiveness to price.

"If price rises, how quickly and easily can producers increase output?" If they can increase quickly (spare capacity, stocks) → PES is elastic. If they cannot (long production time, fixed resources) → PES is inelastic.

Concert tickets — the venue has a fixed number of seats that cannot increase no matter how high the ticket price goes. The supply curve is vertical. When a popular artist announces a tour and demand surges, all the adjustment is in price (price skyrockets).

PED = %ΔQd ÷ %ΔP (usually negative, use absolute value). PES = %ΔQs ÷ %ΔP (always positive). Both measure responsiveness to price changes but for different sides of the market (demand vs supply).

Dividing the wrong way — using %ΔP ÷ %ΔQs instead of %ΔQs ÷ %ΔP. Remember: all elasticity formulas have the RESPONSE on top and the CAUSE on the bottom. Qs RESPONDS to P change, so %ΔQs is the numerator.

When demand shifts, the new equilibrium depends on how easily supply can respond. Elastic supply absorbs the shift mainly through quantity. Inelastic supply absorbs it mainly through price. This is a crucial analytical tool for market analysis.

1) Spare capacity. 2) Availability of stocks/inventories. 3) Mobility of factors of production. 4) Time period. 5) Nature of the product (manufactured vs agricultural).

Supply becomes more elastic as the time period lengthens. In the market period (immediate), supply is perfectly inelastic. In the short run, firms can adjust variable inputs. In the long run, they can build factories and enter new markets — PES is much more elastic.

When demand shifts in a market with inelastic supply, quantity cannot adjust much, so most of the adjustment is in price. A demand increase causes a big price rise; a demand decrease causes a big price fall. This is price volatility.

If a factory has unused machines and idle workers, it can quickly ramp up production when price rises → elastic supply. If the factory is already at full capacity, it cannot easily produce more → inelastic supply.

Commodities typically have inelastic supply — oil wells, farms, and mines cannot quickly increase output. When demand shifts (e.g. economic boom or slump), most of the change appears in price rather than quantity. Adding unpredictable weather makes agricultural prices even more volatile.

1) Momentary/market period — supply is perfectly inelastic (cannot change output at all). 2) Short run — supply is relatively inelastic (can adjust variable inputs like labour but not capital). 3) Long run — supply is relatively elastic (can build new factories, adopt new tech).

Draw a steep (inelastic) supply curve. Shift demand right — show the large price increase and small quantity change. Then shift demand left — show the large price decrease. The diagram demonstrates that inelastic supply amplifies price movements.

Agricultural supply is typically inelastic — crops take months to grow and are affected by unpredictable weather. Manufactured goods have more elastic supply — factories can adjust shifts, increase orders, and scale production more quickly.

If firms hold stock, they can sell from inventory immediately when price rises → elastic supply in the short run. If there are no stocks (fresh food, made-to-order goods), supply is more inelastic because production takes time.

If firms CAN easily increase production when price rises → PES is elastic. If they CANNOT (no spare capacity, long production time, fixed resources) → PES is inelastic. The ease of expanding output is the core idea.

Two factors combine: (1) supply is inelastic — crops take months to grow and cannot be instantly increased. (2) Supply shocks from unpredictable weather frequently shift the S curve. Both inelastic supply AND frequent shifts create extreme volatility.

When coffee prices spike, farmers cannot instantly grow more beans — new coffee trees take 3–5 years to produce. Supply is very inelastic in the short run. In the long run, farmers plant more trees and supply becomes more elastic.

Draw a steep (inelastic) supply curve, shift demand and show the large price change. This analysis appears frequently in data responses about oil, food prices, or housing. Link the inelastic PES to a specific determinant (e.g. time, nature of good) to earn full marks.

It varies widely. Some services have inelastic supply — haircuts are limited by the number of stylists, hospital beds are fixed short-term. Digital services often have very elastic supply — streaming, cloud computing can scale almost infinitely at low marginal cost.

If workers and resources can easily be switched from one use to another (e.g. a clothing factory that can switch between jacket and trouser production), supply is more elastic. If factors are specialised and immobile, supply is more inelastic.