Re: st: When number of regressors greater than the number of clusters in OLS regression

[Steven Samuels <sjhsamuels@earthlink.net>]

More basic questions, Divya:  What is your target population:  the 17  
states (of India, perhaps?) or the entire country?  Were the 17  
states selected from all states by a sampling process?  Or were they  
chosen in some other way--for example, because they had data  
available.  Are all districts from the selected states in your sample?


-Steven
On Sep 1, 2008, at 12:35 PM, Divya Balasubramaniam wrote:


> Dear Dr.Schaffer,
>
> I am using clustering in my analysis and I am having some trouble  
> understanding some of the important issues. I have read several  
> papers you have written on clustering issues and hence I am  
> emailing you to seek help.
>
> I am doing a district level analysis for the census year 2001. I  
> have 436 districts in total coming from 17 States. I run an OLS  
> regression of Share of households having tap water access on  
> several controls variables (I have about 25 Regressors).  I use the  
> STATA command areg Y on X, absorb(State) cluster(state). I have the  
> state fixed effects and clustered by State.
>
> My question is: I have more regresors(25) than the number of  
> clusters(17). I also find in the STATA output that I have F-stat  
> missing. I would like to seek your advice on whether I can make  
> inference by looking at the individual coefficient estimates and  
> the reported robust Standard errors. I did see your comment on this  
> issue on the STATA listserv. However, I could not find answers as  
> to how to fix this problem of having more regressors than the  
> number of clusters.
>
> I will be extremely thankful if you can kindly help me in this regard.
> Sincerely,
> Divya.
> =======================================
> Divya Balasubramaniam
> Economics PhD Student
> Terry College of Business
> University of Georgia
> Athens -30602.
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