How can I forecast over multiple months in the Proc ESM in SAS 9.3?

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Occasional Contributor
Posts: 7

How can I forecast over multiple months in the Proc ESM in SAS 9.3?

Here is my set up:

Proc ESM data = cwork.forecastworked out = forecastedworked Lead = 1;

by clientname;

ID Mon_1_1_YY interval = month accumulate = average;

forecast totalaccts;

run;

I know I can change Lead = 1 to say Lead = 4 or 5 or 6 to get months more than 1 ...

My id variable is a month variable so i'm good there.

I am storing about 6 months of data for history....what happens is that it does forecast all the months I ask for but gives the same value  for each month of that of the first forecasted value...is it because Im not giving it enough historiy?

Hopefully im clear enough on my concern....thanks,.

Respected Advisor
Posts: 2,655

Re: How can I forecast over multiple months in the Proc ESM in SAS 9.3?

You really need to post this in the Forecasting and Econometrics forum. could probably give you an answer within a day.

Steve Denham

SAS Employee
Posts: 416

Re: How can I forecast over multiple months in the Proc ESM in SAS 9.3?

Hello -

There are at least 2 things you might want to need to consider:

  • The default model for ESM is SIMPLE (which will run a simple (single) exponential smoothing model) - this is why all forecasted values are the same.
  • Having 6 points of history only will be a challenge - unless your pattern is truly "stable". Also more advanced models will require more history regardless.
    • As an illustration let's create a subset of sashelp.air which only features the last 6 observations and forecast it with ESM (after inspecting the data I decided to go for a damped trend exponential smoothing model):

          data have;

          set sashelp.air(where=(date ge "01JUL60"d));

          run;

          PROC ESM ESM data=have out=want Lead=3 plot=forecasts;
           date interval=month;
           air / model=DAMPTREND;

          run;

  • The resulting forecasts plot looks like this (for a lead time of 3):

     Short.bmp

  • However, remember that sashelp.air is actually following a seasonal pattern and has a trend component. So your conclusion based on the shorter series might be misleading:

          long.bmp

Hope this helps,

Udo

Occasional Contributor
Posts: 7

Re: How can I forecast over multiple months in the Proc ESM in SAS 9.3?

Thank you!!!!!!!!!!

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