Programming the statistical procedures from SAS

How to specify the slentry and slstay in stepwise or backward regression?

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Regular Contributor
Posts: 173

How to specify the slentry and slstay in stepwise or backward regression?

Hi,

I have never run the stepwise /backward regression before. I am wondering on what basis I can decide the values for slentry (sig level to allow the variable in the model)  and slstay (sig level to keep the variable in the model).

Any guidance/help will be appreciated.

Thanks much,

Ashwini

Respected Advisor
Posts: 2,655

Re: How to specify the slentry and slstay in stepwise or backward regression?

Guidance #1. Don't do backward/forward/stepwise regression.

Guidance #2. See guidance number 1.

There is an abundant number of posts and papers regarding the dangers of this method.  The resulting models have poor predictive ability and the regression parameters range from moderately to severely biased.  See the NESUG paper by Flom and Cassell: "Stopping stepwise: Why stepwise and similar selection methods are bad, and what you should use"  http://www.nesug.org/proceedings/nesug07/sa/sa07.pdf

Still if you must deliberately use a poor tool, stick to the default values.

Steve Denham


Regular Contributor
Posts: 173

Re: How to specify the slentry and slstay in stepwise or backward regression?

Thanks Steve for advising me on this! It's great to know about the latest guidelines on SAS/STAT procedures.

Best,

Ashwini

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