Historically, the production of many perishable foods, such as dairy products, was highly seasonal. Thus, as the supply of those products fluctuated, prices tended to fluctuate tremendouslylong dash—typically by 25 to 50 percent or morelong dash—over the course of the year. One impact of mechanical refrigeration, which was commercialized on a large scale in the last decade of the nineteenth century, was that suppliers could store perishables from one season to the next. Economists have estimated that as a result of refrigerated storage, wholesale prices rose by roughly 10 percent during peak supply periods, while they fell by almost the same amount during the off season.

Feedback systems do not always involve negative feedback. economic inflation, which is evidenced by continually rising prices, is a positive feedback system. a positive feedback control system, as shown on the right, adds the feedback signal to the input signal, and the resulting signal is used as the input to the process. a simple model of the price-wage inflationary spiral is shown on the right. add additional feedback loops, such as legislative control or control of the tax rate, to stabilize the system. it is assumed that an increase in workers’ salaries, after some time delay, results an increase in prices. under what conditions could prices be stabilized by falsifying or delaying the availability of cost-ofliving data? how would a national wage and price economic guideline program affect the feedback system?