Conditional logistic regression

[UcheOkoro]

Hello,

Please, I am working on some conditional logistic regression and part of the output is following

I cannot find the meaning of "number of observations informative " and why it is low.

The following is my code

proc logistic data = Avera_matched_data ;
 CLASS telemed_use(DESC)  chronic_dialysis(DESC) total_sofa1_ed2(DESC) mode_arrival(DESC) pmh_cancer(DESC) pmh_diabetes(DESC) 
       pmh_asthma(DESC) pmh_chf(DESC) pmh_hypertension(DESC) pmh_dialysis(DESC)
        pmh_copd(DESC) pmh_cirrhosis(DESC) pmh_transplant(DESC) Lactate1_cat(DESC) Age2(DESC) sex(DESC);
  model new_dialysis(event='1') = telemed_use apache_total surgery chronic_dialysis total_sofa1_ed2 mode_arrival pmh_cancer 
pmh_diabetes pmh_asthma pmh_chf pmh_hypertension pmh_dialysis pmh_copd pmh_cirrhosis pmh_transplant Lactate1_cat Age2 infection_ed_source2 sex /MAXITER=100 ITPRINT;
  strata _MatchID;
  ODS OUTPUT ParameterEstimates=new_dialysis1 ODDSRATIOS=lgsodds;
  BY _Imputation_;
   title " Model of New Dialysis by telemed";
run;

Thank you in advance for your assistance.

[StatDave · Accepted solution]

As stated in the description of the STRATA statement:

"Strata that contain only events or only non-events are reported in this table, but such strata are uninformative and are not used in the analysis."

So, that is the count of all observations not involved in those uninformative strata.

[UcheOkoro]

Thank you so much for your help.