st: Date: Thu, 5 Feb 2004 16:05:09 -0600

["Cram, Peter" <peter-cram@uiowa.edu>]

Dear Statalist,

I am running the following logistic regression model.


xi: logistic mort30 SpecHosp age i.sex i.race alcohol_ex arrhyth_ex



However I have hospitals clustered within regions (variable hrrnum) and
patients clustered within hospitals (variable prov_num).

I have been able to run my regression with a single cluster included:

xi: logistic mort30 SpecHosp age i.sex i.race alcohol_ex arrhyth_ex, cluster
(hrrnum)


but am unable to run the model with 2 clusters because I receive error
messages each time I do so.

xi: logistic mort30 SpecHosp age i.sex i.race alcohol_ex arrhyth_ex, cluster
(hrrnum) cluster (prov_num)


How can I account for the 2 levels of clustering in my data in my regression
model?

Thanks,
Pete 
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