Summary of Understanding Economic Elasticity

## Introduction Price Elasticity of Supply (PES) measures how much the quantity supplied of a good changes when its price changes, holding all else constant. Simply put: how responsive is supply to price changes? > **Definition:** Price Elasticity of Supply (PES) is the percentage change in quantity supplied divided by the percentage change in price. ## Basic Concepts ### Formula and Sign - Formula: $$\text{PES} = \dfrac{\%\ \text{change in quantity supplied}}{\%\ \text{change in price}}$$ - Since the supply curve is generally upward-sloping, PES will always be positive or zero. > **Definition:** If PES $>1$, supply is elastic; if PES $<1$, supply is inelastic; if PES $=0$, supply is perfectly inelastic; if PES $=\infty$, supply is perfectly elastic. ### Interpretation - PES > 1: quantity supplied responds more than proportionally to price (elastic supply). - PES < 1: quantity supplied responds less than proportionally to price (inelastic supply). - PES = 0: quantity does not change even if the price changes (vertical curve). - PES = \infty: price does not change even if the quantity varies (horizontal curve). ## Step-by-Step Practical Example Two clothing manufacturers, A and B, each sell garments at $10 and offer 100 units daily. Following a price increase to $12 due to higher demand: - Producer A: increases from 100 to 110 units. - Change in quantity: $\dfrac{110-100}{100} = 0.10 = 10\%$ - Change in price: $\dfrac{12-10}{10} = 0.20 = 20\%$ - $$\text{PES}_A = \dfrac{10\%}{20\%} = 0.5$$ (inelastic supply) - Producer B: increases from 100 to 140 units. - Change in quantity: $\dfrac{140-100}{100} = 0.40 = 40\%$ - Change in price: $20\%$ (same as above) - $$\text{PES}_B = \dfrac{40\%}{20\%} = 2$$ (elastic supply) > Did you know that the same percentage price increase can result in vastly different supply responses depending on the supplier's production capacity and resources? ## Factors Affecting Supply Elasticity - Time available to adjust production: - In the short run, supply is typically more inelastic; in the long run, it's usually more elastic. - Availability of productive inputs (land, machinery, labor). - Ease of product storage (non-perishable goods are more elastic). - Idle capacity and technological flexibility. - Ease of entry and exit for firms in the market. Comparison Table: Elastic vs. Inelastic Supply | Characteristic | Elastic Supply | Inelastic Supply | |---|---:|---:| | Percentage Change in Quantity Supplied | Greater than the percentage change in price | Less than the percentage change in price | | Adjustment Time | Long or sufficient | Short or limited | | Storage | Easy (non-perishable) | Difficult (perishable) | | Typical Example | Manufactured goods with idle capacity | Perishable agricultural products | ## Extreme Cases: PES = 0 and PES = \infty - PES = 0 (perfectly inelastic): supply is vertical. Example: perishable flowers available at a given moment; the quantity cannot be increased even if the price rises. - PES = \infty (perfectly elastic): supply is horizontal. The producer sells any quantity at price P but will not accept a lower price. ## Applied Activities (Brief Guide) 1. Analyze the following table (provided in the original text) and draw the supply curve. Calculate the PES when the price falls from $90 to $80 and then to $50 per sack using the previous formula. 2. In pairs, discuss why producers A and B from the example section have different PES values. Consider: installed capacity, ease of hiring labor, access to inputs, seasonality. ## Real-World Application: The Cashew Nut Industry in Tanzania - Production depends on climate and investment in plantations, making supply unpredictable and potentially relatively inelastic in the short term. - The government sets indicative prices to reduce volatility and, in surplus years, purchases excess stock to protect producers. - Adding local processing capacity could increase long-term elasticity and add value to exports.