With the A2 Essay paper next week I thought something on the kinked demand curve might be useful. I alluded to in a previous post that one model of oligopoly revolves around how a firm perceives its demand curve. The model relates to an oligopoly in which firms try to anticipate the reactions of rivals to their actions. As the firm cannot readily observe its demand curve with any degree of certainty, it has got to estimate how consumers will react to price changes.
In the graph below the price is set at P1 and it is selling Q1. The firm has to decide whether to alter the price. It knows that the degree of its price change will depend upon whether or not the other firms in the market will follow its lead. The graph shows the the two extremes for the demand curve which the firm perceives that it faces. Suppose that an oligopolist, for whatever reason, produces at output Q1 and price P1, determined by point X on the graph. The firm perceives that demand will be relatively elastic in response to an increase in price, because they expects its rivals to react to the price rise by keeping their prices stable, thereby gaining customers at the firm’s expense. Conversely, the oligopolist expects rivals to react to a decrease in price by cutting their prices by an equivalent amount; the firm therefore expects demand to be relatively inelastic in response to a price fall, since it cannot hope to lure many customers away from their rivals. In other words, the oligopolist’s initial position is at the junction of the two demand curves of different relative elasticity, each reflecting a different assumption about how the rivals are expected to react to a change in price. If the firm’s expectations are correct, sales revenue will be lost whether the price is raised or cut. The best policy may be to leave the price unchanged.
With this price rigidity a discontinuity exists along a vertical line above output Q1 between the two marginal revenue curves associated with the relatively elastic and inelastic demand curves. Costs can rise or fall within a certain range without causing a profit-maximising oligopolist to change either the price or output. At output Q1 and price P1 MC=MR as long as the MC curve is between an upper limit of MC2 and a lower limit of MC1.
Criticisms of the kinked demand curve theory.
Although it is a plausible explanation of price rigidity it doesn’t explain how and why an oligopolist chooses to be a point X in the first place. Research casts doubt on whether oligopolists respond to price changes in the manner assumed. Oligopolistic markets often display evidence of price leadership, which provides an alternative explanation of orderly price behaviour. Firms come to the conclusion that price-cutting is self-defeating and decide that it may be advantageous to follow the firm which takes the first steps in raising the price. If all firms follow, the price rise will be sustained to the benefit of all firms.
If you want to gradually build the kinked demand curve model download the powerpoint by clicking below.