Winters' multiplicative model: prediction intervals for forecasts

This macro lets you specify a confidence level other than 95% for the prediction intervals for the forecasts when using Winters' Method and a multiplicative model is appropriate.

Download the Macro

Be sure that Minitab knows where to find your downloaded macro. Choose Tools > Options > General. Under Macro location browse to the location where you save macro files.


If you use an older web browser, when you click the Download button, the file may open in Quicktime, which shares the .mac file extension with Minitab macros. To save the macro, right-click the Download button and choose Save target as.

Required Inputs

  • A column of time series data
  • Seasonal length
  • Level, trend, and seasonal weights
  • Desired number of forecasts
  • Desired confidence level for the prediction intervals

Running the Macro

The syntax used to run the macro varies slightly depending on the version you are using.

Suppose the data are in C1, the seasonal length is 2, the level, trend, and seasonal weights are .2 .2 .2 respectively, you want 2 forecasts, and you want 99% prediction intervals stored in the Worksheet.

To run the macro, choose Edit > Command Line Editor and type:
WEIGHT 0.2 0.2 0.2;
CONF 99.

Click Submit Commands.

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