statistical power for logistic regression

noetsi

No cake for spunky
how do you find out what the power of your test is for logistic regression? I have never run across this in SAS.

staassis

Active Member
I believe the likelihood ratio, Wald and deviance tests have slightly different power functions. You can always calculate the power via Monte Carlo on a grid of parameter values and then interpolate in between with cubic splines. But there are probably simpler approaches. Somebody somewhere must have tabulated the power functions already.

noetsi

No cake for spunky
I am sure sas has a module that calculates power, I know SPSS does. I just do not know where it is.

hlsmith

Less is more. Stay pure. Stay poor.
I was surprised, that looked like a pretty good power procedure for SAS. I was gonna recommend a Monte Carlo simulation, but @Dason link definitely seem appropriate.

noetsi

No cake for spunky
https://support.sas.com/documentati...fault/viewer.htm#statug_power_a0000001016.htm

I'm guessing this isn't what you want? Because all I did was click on the first Google result for "sas logistic regression power"
I was relying on experts here rather than searching. I don't always do well on searching [I often get confused with SAS documentation]. Given that I have no theory to guess at the distribution or effective size of much of what I do I am going to have problems using that. I work with vocational rehabilitation, and if there is any theory for much of it I do not know it. I work with raw data and little else.

But its useful to find out about Proc Power. Never heard of that.

Dason

Ambassador to the humans
Given that I have no theory to guess at the distribution or effective size of much of what I do I am going to have problems using that.
I'm not sure how you planned on doing any sort of power calculation then.

noetsi

No cake for spunky
Software I used before asked only for an estimated effect size, and an alpha level I thought (as well as a sample size which I know).

Dason

Ambassador to the humans
Was that for logistic regression or just a linear regression