Policy intervention and forecasting: An application to minimum wages

This paper examines the forecasting implications of incorporating policy effects into the structure of unconditional time series models. The forecasting model is applied to the Puerto Rican experience with minimum wages from 1953 to 1982. The empirical results suggest that significant disemployment and unemployment followed the imposition of economy-wide minimum wages in 1974. The growth of employment suffered and the aggregate unemployment rate reached an unprecedented level. Multivariate time-series models for the employment-population ratio and the unemployment rate capture these effects well. They also forecast more accurately than unvariate and intervention models over the ex post period, 1983–1984. It is argued that models that combine subject matter-specific structure within a dynamic time-series framework greatly help to satisfy demands for theoretical consistency and forecast accuracy. Multivariate time-series models play an important complementary role in the structural modelling of economic policy analysis. This is particularly so when limitations of either data or theory preclude complete specification of structural equations.