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Using price elasticities

15 二月, 2016 - 09:58

Knowledge of elasticity values is useful in calculating the price change required to eliminate a shortage or surplus. For example, shifts in the supply of agricultural products can create surpluses and shortages. Because of variations in weather conditions, crop yields cannot be forecast accurately. In addition, on account of the low elasticity of demand for such products, low crop yields can increase prices radically, and bumper harvests can have the opposite impact.

Consider Figure 4.4. Econometricians tell us that the demand for foodstuffs is inelastic, so let us operate in the lower (inelastic) part of this demand, D. A change in supply conditions (e.g. a shortage of rain and a poorer harvest) shifts the supply from S_1 to S_2with the consequence that the price increases from P_1 to P_2. In this illustration the price increase is substantial. In contrast, with a relatively flat, or elastic, demand, D', through the initial point A, the shift in the supply curve has a more moderate impact on the price (from P_1 to P_3), but a relatively larger impact on quantity traded.

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Figure 4.4 The impact of elasticity on quantity fluctuations 
 

In the lower part of the demand curve D, where demand is inelastic, e.g. point A, a shift in supply from S_1 to S_2 induces a large percentage increase in price, and a small percentage decrease in quantity demanded. In contrast, for the demand curve D' that goes through the original equilibrium, the region A is now an elastic region, and the impact of the supply shift is contrary: the %\DeltaP is smaller and the %\DeltaQ is larger.