Analytics Magazine Analytics Magazine, July/August 2014 | Page 76

FO RE CAST ING Figure 4. IBM SPSS input worksheet (showing the “Non-Stop” movie daily box-office returns). products from different categories, specifically Minitab, IBM SPSS and NCSS on the “Non-Stop” movie data. IBM SPSS falls into the automatic forecasting category; Minitab and NCSS are semiautomatic products. A caveat: This is not meant to be a critical review of any product mentioned. I let IBM SPSS first do the analysis of the movie data via its automatic mode, called “Expert Modeler” (i.e., choose the model and its parameters and get the forecasts). Figure 4 shows superimposed screen shots of IBM SPSS’ worksheet, showing the “Non-Stop” daily domestic box-office gross and the menu system to start the automatic forecasting procedure. The program then gave its recommended model, Brown’s method for data with linear trend, which uses one smoothing constant to estimate the intercept and slope of the fitted line (as compared to Holt’s method, which uses two independent smoothing constants) [1]. IBM SPSS’ accompanying statistics, forecast plot and additional output are shown in Figure 5. Figure 5: IBM SPSS’ results of “automatic” forecasting of the “Non-Stop” data. 76 | A N A LY T I C S - M A G A Z I N E . O R G W W W. I N F O R M S . O R G