Spurious Volatility in Historical Unemployment Data
证明1930年前后失业率波动性的差异是数据收集方法改进造成的假象；用旧方法重建战后数据后发现其波动性与战前相当，并据此修正了历史数据。
This paper shows that the stabilization of the unemployment rate between the pre-1930 and post-1948 eras is an artifact of improvements in data collection procedures. Prewar methods are used to construct postwar unemployment data that are consistent with the historical data. The constructed postwar series is nearly as volatile as the pre-1930 unemployment data. The constructed postwar data are systematically more volatile than the actual postwar data because the cyclical behavior of the labor force and productivity are misspecified in the construction procedures. The relationship between the actual and constructed postwar unemployment series is used to construct new historical data.