When Real GDP Increases

More than a quarter of the people wishing to work were unable to find a job. Countless others, no doubt, had given up even looking for a job and were out of the labor force. The experience of the 1920s and 1930s tells us that when real GDP increases, unemployment tends to decline and vice versa. We say that unemployment is countercyclical, meaning that it typically moves in the direction opposite to the movement of real GDP. An economic variable is procyclical if it typically moves in the same direction as real GDP, increasing when GDP increases and decreasing when GDP decreases. The countercyclical behavior of unemployment is not something that is peculiar to the Great Depression; it is a relatively robust fact about most economies. It is also quite intuitive: if fewer people are employed, less labor goes into the production function, so we expect output to be lower. An event occurred in September 1929 that, at least with hindsight, marks a turning point. The stock market, as measured by the Dow Jones Industrial Average, had been increasing until that time but then decreased by 48 percent in less than 2.5 months. The value of the stock market is a measure of the value, in the minds of investors, of all the firms in the economy. Investors suddenly decided that the US economy was worth only half what they had believed three months earlier. It is unlikely that two such dramatic economic events occurred at almost the same time and yet are unconnected. We should not make the claim that the stock market crash caused the Great Depression. But the stock market decrease was correlated with declining output in the early days of the Great Depression. Correlation is distinct from causation. It is possible, for example, that the stock market crash and the Great Depression were both caused by some other event. Toolkit: Section 16.13 “Correlation and Causality” Correlation is a statistical measure of how closely two variables are related. If the two variables tend to increase together, we say that they are “positively correlated”; if one increases when the other decreases, then they are “negatively correlated.” If the relationship between the two variables is an exact straight line, we say that they are “perfectly correlated.” The fact that two variables are correlated does not necessarily mean that changes in one variable cause changes in the other. The toolkit contains more information.  “Major Macroeconomic Variables, 1920–39*” also contains information on the price level and the inflation rate. The most striking fact from this table is that the price level declined over this period—on average, goods were considerably cheaper in dollar terms in 1940 than they were in 1920. We see this both from the decrease in the price level and from the fact that the inflation rate was negative in several years (remember that the inflation rate is the growth rate of the price level). If we look at the more recent history of the United States and at most other countries, we rarely observe negative inflation. Decreasing prices are an unusual phenomenon. Other countries had similar experiences during this time period. “The Great Depression in Other Countries” shows that France, Germany, and Britain all experienced very poor economic performance in the early 1930s. Output was lower in each country in 1933 compared to four years earlier, and each country also saw a decline in the price level.