st: Convergence not acheived

["Momplaisir, Florence" <Florence.Momplaisir@tuhs.temple.edu>]

Hello all,

I'm using a mixed effect model to assess factors associated with getting an elective c-section among HIV + women. I used these commands (listed below) but I'm getting an error message saying that convergence is not acheived. My cell sizes vary between 3 and 111 and it is difficult for me to collapse things further (wouldn't make clinical sense). What should I do in that case?
xtset Stateno
.   xi: xtlogit elective_c i.adequate_pre1 i.delivery_agegrp1 i.r
> ace_cat1 i.illdrug i.C_RPT i.gestage1 if viralsup==2, or pa c(e
> xc)
i.adequate_pre1   _Iadequate__0-2     (naturally coded; _Iadequat
> e__0 omitted)
i.delivery_ag~1   _Idelivery__0-2     (naturally coded; _Ideliver
> y__0 omitted)
i.race_cat1       _Irace_cat1_0-2     (naturally coded; _Irace_ca
> t1_0 omitted)
i.illdrug         _Iilldrug_0-1       (naturally coded; _Iilldrug
> _0 omitted)
i.C_RPT           _IC_RPT_1-2         (_IC_RPT_1 for C_RPT==False
>  omitted)
i.gestage1        _Igestage1_0-1      (naturally coded; _Igestage
> 1_0 omitted)
note: _Iilldrug_1 dropped because of collinearity
note: _Igestage1_1 dropped because of collinearity
estimates diverging (correlation > 1)
r(430);



Florence Momplaisir, MD MSHP
Infectious Diseases Fellow
Temple University Hospital

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