How do you make the forecasts produce only positive numbers in SAS/ETS

[deleted_user]

Hello SAS gurus,

My question is regarding SAS/ETS. Is there a way to force the forecasts to only produce positive numbers?

Also can you select a list of time series models the automatic models selection can choose from in TSFS?

Thanks,

AYDot

[udo_sas]

Hello AYDot -
The way I look at it is as follows: the forecasted values should be derived by the data which you have at hand - which could mean that you are creating negative forecast (if you are facing a negative trend for example).

If you have additional knowledge about the business question at hand (for example: when forecasting sales non-negative numbers might not make a lot of sense) you can go ahead and modify the output of the statistical forecasting engine in a post-process step.

As such you might want to consider the follow approach:
Start with creating forecasted values using SAS/ETS. If the prediction is negative simply set the values (prediction and confidence interval) to 0 using a data step for example.

Hope this makes sense.
Regards,
Udo