st: asclogit error: "this exceeds the limit of 800 for factors"

[Andreas Schmid <andreas.schmid@uni-bayreuth.de>]

Dear All,

I try to analyze hospital choice behavior of patients using the asclogit 
command. The following error code occures:

"variable Hospital_ID has 1936 categories; this exceeds the limit of 800 
for factors"

What does it mean and how can I work around it?


Some more background information:

The error message is the same, no matter which particular specification 
of the asclogit setup I use. I have data on about 2000 hospitals and use 
data on about 2,000,000 patients. A choice set of about 15 nearby 
hospitals is assigned to each patient, including the actual choice.  I 
intend to use about 5 case specific variables and 1 alternative specific 
variable (distance). The data is in long format, resulting in the 
following structure:

Patient_ID | Hospital_ID | Choice_Indicator | distance | hosp_var1 | 
hosp_var2 | hospital_var3 | patient_var1 | patient_var2

My Stata Version is StataSE 11 (64-bit).

So far I couldn't find any useful information on this specific problem - 
I have searched the statalist archive, read all kind of help files and 
googled a lot... I really appreciate your help!

Thanks a lot!

Andreas
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