st: xtmelogit_ 3200 conformability error

[Tara Roberts <tpearson@uoguelph.ca>]

Hello All, 

I am currently trying to run a random effects model looking at the prevalence of e. coli within flock by producer type and sample type, and clustering by producer ID as my upper level (more than 1 flock per producer was sampled) using the following command line in Stata 10.1;

 xi: xtmelogit ecoli i.prodcode i.sampcode || prodid:, or

Where: ecoli is my outcome variable (0/1 for negative/positive)
       prodcode is the type of farm from which samples were obtained(0/1/2)
       sampcode is the type of sample collected (1/2/3/4/5)
       prodid is producer identification number (1-45)

I get the following error messages:

i.prodcode        _Iprodcode_1-3      (naturally coded; _Iprodcode_1 omitted)
i.sampcode        _Isampcode_1-5      (naturally coded; _Isampcode_1 omitted)
                       *:  3200  conformability error
     _xtgm_estimate_re():     -  function returned error
  _xtgm_estimate_re_st():     -  function returned error
                 <istmt>:     -  function returned error


By reading the archives on Statalist I have grasped that I am likely trying to combine two matrices which are not conformable. However, I am still not sure on how to go about solving this problem (A different command/model or using Mata?)

Any guidance would be sincerely appreciated. 

Cheers,

Tara Roberts, MSc.
PhD Candidate- Epidemiology
Department of Population Medicine
Ontario Veterinary College
University of Guelph

Email: tpearson@uoguelph.ca
       tara.pearson@phac-aspc.gc.ca

Phone: (519)532-9819



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