— Ch. 1 · Defining Price Stickiness —
Nominal rigidity.
~4 min read · Ch. 1 of 6
In 1936, John Maynard Keynes published The General Theory of Employment, Interest and Money. Within its pages, he described a situation where nominal wages display downward rigidity. Workers are reluctant to accept cuts in their pay. This resistance creates involuntary unemployment as wages fail to adjust to equilibrium levels quickly enough. Complete nominal rigidity occurs when a price remains fixed for a relevant period. A contract might set the price of a good at $10 per unit for an entire year regardless of supply changes. Partial nominal rigidity allows prices to adjust but less than under perfect flexibility. Legal limits in regulated markets may restrict how much a price can change within a given year. These rigidities explain why markets do not always clear immediately.
Empirical Evidence And Data
Statistical agencies collect tens of thousands of price quotes each month to construct the Consumer Price Index. In France and the UK during the late 1990s, 19% of prices changed every month on average. This implies that an average price spell lasts about 5.3 months. US data from 1998 to 2005 showed similar patterns with slight variations across countries like Germany and Italy. Removing temporary sales raises the mean spell duration considerably. In the United States, the reference price remained unchanged for an average of 14.5 months after excluding sales. Some items like gasoline vary frequently resulting in many short price spells. Other goods such as champagne or restaurant meals stay fixed for extended periods. The distribution of durations heavily influences our understanding of economic behavior rather than simple averages alone.