Multivariate regression analysis is employed to predict the prices of
mechanical and electric products according to historical prices. Because there are many
years in which the product price data are unavailable, a price index is introduced into
the prediction. Thus, the problem of forecasting the product prices is converted into the
one of forecasting the price indexes. In the regression analysis, the time and price
policies are taken as significant factors of the price index. The characteristics of the
fitting values of the price index are also discussed.