Hi,

I am working with National Inpatient Sample (NIS). Considering the survey design, I am running the codes below:
Code:
clear
set more off
use "C:\Users\mjafaribidgoli\Desktop\HCUP\HCUP_NIS_2016\NIS_2016_Core_cleaned_selected.dta"
calipmatch, gen(pairid) case(mastectomy) max(1) calipermatch(charlindex) caliperwidth(1) exactmatch( AGE LOS ) ///matched on AGE and Length of Stay ///matched on AGE and LOS
drop if pairid==.
svyset HOSP_NIS [pw= DISCWT ], strata( NIS_STRATUM )
svy, subpop(breast_cancer):clogit depression mastectomy charlindex i.health_ins i.patient_resid i.race i.household_inc, group(pairid)
.

I get this error:
Code:
the group() variable is not nested within the final stage sampling units
.

I appreciate if anyone can help me with this.