How could everyone have been so wrong? Forecasting the Great Depression with the railroads

Contemporary observers viewed the recession that began in the summer of 1929 as nothing extraordinary. Using a neglected data set of forecasts by railroad shippers, we find that business was surprised by the magnitude of the Great Depression. We show that simple time series methods would have produced much smaller forecast errors than those indicated by the surveys, thus indicating that the survey forecasts were formed using more information than just the past history of the series. The depth and duration of the depression was beyond the experience of business, which appears to have believed that recovery would happen quickly as in previous recessions. Forecasts of inflation are then constructed using the survey forecasts. We find little evidence that the deflation that occurred during the Great Depression was foreseen, thus emphasizing the role of debt deflation in the propagation of the depression.