Help using Base SAS procedures

Need help with a clustering problem

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Occasional Contributor
Posts: 7

Need help with a clustering problem

I'd like to run a regression where the dependent variable (say, stocks' abnormal returns) are related to a few explanatory variables.  The problem is that all the stocks come from the same industry,and so the error terms are probably correlated.  Is there a SAS function that can take care of this problem?  Pleade note that the data are NOT time-series data.  The abnormal returns are measured at one single point in time.  In other words, the data are just cross-sectional data.  Thanks.

Frequent Contributor
Posts: 83

Re: Need help with a clustering problem

Your best bet is likely to either use GEE (Generalized Estimating Equations) in Proc Genmod SAS/STAT(R) 9.22 User's Guide or here are another couple of ways to use clusters in SAS http://nesug.org/proceedings/nesug06/an/da01.pdf Hope this helps.

Occasional Contributor
Posts: 7

Re: Need help with a clustering problem

Thanks, overmar.  I've tried to learn how to use Proc Genmod and also Proc Surveyreg.  But I don't think they can be used in my case.  My sample all comes from the same industry, and so there is only class of observations (i.e., no multiple clusters).  I just want to run a regression on this sample.  Since the error terms may be correlated, I'd like to know if there a SAS function that can adjust the standard errors of the coefficients to account for the correlation.  Thanks.

Super User
Posts: 19,822

Re: Need help with a clustering problem

You're looking for a way to adjust for dependent data.

I don't believe there's an easy way. One is to cluster the data, if you know what the clusters are, but since you have only one cluster I'm not sure. More likely it seems like its simply a limitation of your analysis rather than something you can control for in any way. 

Occasional Contributor
Posts: 7

Re: Need help with a clustering problem

Thanks, Reeza.  Sorry I didn't thank you earlier.  I got a flu that knocked me out during the past two weeks.

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