Lets suppose we have the following data


Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input double(wcobs area q102 q116 vdd)
0 1 1 2 .
0 1 1 2 .
0 1 1 2 .
0 1 2 2 0
0 1 2 1 .
0 1 2 2 0
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 2 1
0 1 1 2 .
0 1 2 2 0
0 1 2 2 0
0 1 2 2 .
0 1 2 1 .
. 1 2 1 .
0 1 2 1 .
0 1 2 2 0
0 1 1 1 .
0 1 1 1 0
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 0
0 1 2 1 .
0 1 1 1 0
0 1 2 2 0
0 1 1 1 .
0 1 2 2 .
0 1 2 2 .
0 1 1 2 0
0 1 2 1 .
1 1 1 2 0
0 1 1 1 .
0 1 2 1 .
0 1 2 2 .
0 1 2 2 1
0 1 1 1 .
0 1 1 1 .
0 1 2 1 1
0 1 1 1 1
0 1 1 1 0
0 1 1 1 .
0 1 2 1 .
0 1 2 1 1
0 1 1 1 .
0 1 1 1 .
0 1 1 2 .
0 1 2 2 .
0 1 2 1 .
0 1 1 1 .
0 1 2 2 .
0 1 2 2 .
0 1 2 2 .
0 1 2 2 .
0 1 2 1 .
0 1 1 2 1
0 1 2 1 .
0 1 2 1 1
0 1 1 1 1
1 1 1 2 0
0 1 2 2 .
0 1 2 2 .
0 1 2 1 .
0 1 2 2 .
0 1 1 1 0
0 1 2 2 .
0 1 2 2 .
0 1 1 2 .
0 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 2 1 0
0 1 1 1 0
0 1 2 1 0
0 1 2 1 .
. 1 2 1 .
0 1 1 1 0
0 1 1 1 .
0 1 1 2 .
0 1 1 1 1
. 1 2 2 .
0 1 1 2 .
0 1 1 1 .
0 1 2 1 .
0 1 1 1 0
0 1 1 1 .
0 1 1 2 0
0 1 1 2 .
0 1 2 1 .
0 1 1 1 .
0 1 2 1 0
0 1 1 2 .
0 1 2 2 .
0 1 1 1 .
0 1 2 2 0
0 1 1 2 0
0 1 2 1 .
0 1 2 1 1
0 1 1 1 0
0 1 2 1 1
0 1 2 2 .
0 1 2 1 .
0 1 2 2 .
0 1 2 2 0
0 1 2 1 .
0 1 1 1 0
0 1 1 1 .
0 1 2 1 .
0 1 2 2 .
0 1 2 1 0
0 1 2 1 .
0 1 1 2 1
0 1 2 2 .
0 1 2 2 1
0 1 1 2 .
0 1 1 1 .
0 1 1 2 .
0 1 2 2 .
0 1 2 2 0
0 1 1 2 .
0 1 2 1 0
0 1 1 2 .
0 1 1 2 0
0 1 1 1 1
0 1 2 1 0
0 1 1 2 .
0 1 1 2 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 1
0 1 2 1 0
0 1 2 1 .
0 1 1 2 .
0 1 2 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 1 1 0
0 1 1 2 .
0 1 1 2 .
0 1 2 2 .
0 1 2 1 0
0 1 1 1 0
0 1 2 1 0
0 1 1 1 .
0 1 1 1 0
0 1 2 1 0
0 1 1 1 0
0 1 2 1 .
0 1 1 1 .
0 1 2 1 0
0 1 1 2 .
0 1 1 1 0
0 2 2 1 .
0 2 2 2 0
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 .
0 2 1 2 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 1
0 2 2 1 1
0 2 2 1 1
0 2 1 1 1
0 2 1 1 .
0 2 1 1 1
0 2 2 1 .
0 2 2 1 .
0 2 2 2 .
0 2 1 1 0
0 2 2 1 0
0 2 2 1 .
0 2 2 1 1
0 2 1 2 .
0 2 2 1 .
0 2 2 2 .
0 2 2 2 1
0 2 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 0
0 2 2 2 .
0 2 2 2 .
0 2 1 2 .
0 2 2 2 .
0 2 1 1 0
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 1 2 2 .
0 2 1 2 0
0 2 1 1 .
0 2 2 1 .
0 2 1 2 .
0 2 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 2 2 .
0 2 2 2 .
0 2 1 1 0
0 2 2 1 .
0 2 1 1 .
0 2 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 1
0 2 2 1 .
0 2 1 2 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 2 1
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 .
0 2 1 1 1
0 2 2 8 1
0 2 2 1 .
0 2 1 1 1
0 1 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 .
0 2 2 2 .
0 2 1 2 .
0 2 1 2 0
0 2 2 1 0
0 2 1 2 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 0
0 2 2 2 .
0 2 2 1 .
. 2 2 1 .
0 2 2 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 0
0 2 1 1 0
0 2 1 1 0
0 2 2 2 .
0 2 1 1 1
0 2 1 1 1
0 1 2 1 .
0 1 2 1 .
0 1 1 1 0
0 1 1 2 .
0 1 2 2 .
0 1 2 1 .
0 1 1 1 .
0 1 1 2 .
0 1 1 1 0
0 1 2 1 .
0 1 2 1 .
0 1 1 2 0
0 1 2 1 0
0 1 2 2 0
0 1 1 1 .
0 1 1 1 .
0 1 2 2 .
0 1 2 2 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 1 1 0
0 1 2 1 .
0 1 1 2 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 0
0 1 2 1 0
0 1 2 1 .
0 1 2 1 0
0 1 1 1 0
0 1 1 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 2 .
0 1 2 1 0
0 1 1 1 0
0 1 2 1 .
0 1 2 1 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 2 1 0
0 1 2 1 .
0 1 2 1 .
0 1 2 1 .
0 1 1 1 0
0 1 2 1 .
0 1 1 1 .
0 1 2 2 0
0 1 1 1 .
0 1 1 1 0
0 1 2 1 .
0 1 1 1 .
0 1 2 2 .
0 1 1 2 .
0 1 1 1 .
0 1 1 1 0
0 1 1 1 .
0 1 2 1 .
0 1 2 2 .
0 1 2 1 0
0 1 2 2 .
0 1 1 1 .
0 1 2 1 .
0 1 2 2 .
0 1 2 2 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 0
0 1 2 2 .
. 1 1 1 .
0 1 1 2 0
0 1 2 1 0
0 1 2 1 .
0 1 1 1 0
0 1 2 1 0
0 1 1 1 .
0 1 2 1 0
0 1 2 1 0
0 1 2 1 0
0 1 1 2 .
0 1 2 2 .
0 1 2 2 0
0 1 2 2 .
0 1 2 2 0
0 1 2 2 .
0 1 1 2 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 0
0 1 1 2 .
0 1 2 1 .
0 1 2 2 0
0 1 2 1 .
0 1 1 2 0
0 1 2 1 0
0 1 2 1 .
0 1 2 2 .
0 1 1 1 0
0 1 1 1 .
0 1 1 2 .
0 1 1 1 .
0 1 1 1 .
0 1 1 2 .
0 1 2 1 0
0 1 1 1 .
0 1 1 1 0
0 1 1 1 .
0 2 1 1 .
0 1 2 1 0
0 1 1 1 0
0 1 1 1 0
0 1 1 2 .
0 1 1 1 0
0 1 2 1 .
0 1 1 1 0
0 1 2 1 .
0 2 1 1 0
0 2 1 1 .
0 2 2 1 1
0 2 2 1 .
0 2 2 2 1
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 2 2 0
0 2 1 1 .
0 2 2 1 0
0 2 2 1 .
0 2 2 1 0
0 2 2 1 .
0 2 1 1 .
0 2 1 1 0
0 2 2 1 0
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 2 .
0 2 1 2 0
0 2 1 1 .
0 2 2 1 0
0 2 2 1 .
0 2 1 1 0
0 2 2 1 0
0 2 1 1 .
0 2 2 1 0
0 2 2 1 0
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 1
0 2 1 1 .
0 2 1 1 .
0 2 2 1 0
0 2 2 1 .
0 2 2 1 0
0 2 1 1 .
0 2 2 1 .
0 2 1 1 0
0 2 1 2 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 2 1 0
0 2 1 2 .
0 2 1 1 .
. 2 2 1 .
0 2 2 1 0
0 2 1 1 .
0 2 2 2 .
0 2 1 1 0
0 2 2 1 0
0 2 1 1 0
0 2 1 1 .
0 2 2 1 .
0 2 2 2 .
0 2 1 1 .
0 2 2 2 1
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 0
0 2 2 1 0
0 2 1 1 .
0 2 2 1 .
0 2 1 1 0
0 2 2 1 .
0 2 1 1 0
0 2 1 1 .
0 2 2 2 .
0 2 1 1 0
0 2 1 1 1
0 2 1 1 0
0 2 1 1 .
0 2 2 1 1
0 2 2 1 0
0 2 1 1 0
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 0
0 2 2 1 .
0 2 1 2 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 0
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 1
0 2 2 1 1
0 2 1 1 .
0 2 2 1 .
0 2 1 2 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 0
0 2 1 1 0
0 2 1 1 .
. 2 1 2 1
0 2 1 2 0
0 2 2 2 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 1
0 2 1 2 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 1
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 2 .
0 2 1 1 .
0 2 2 2 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 2 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 2 .
0 2 1 2 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 1
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 .
0 2 1 2 0
0 2 1 1 .
0 2 1 1 1
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 0
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 2 .
0 2 1 2 .
0 2 2 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 2 .
0 2 2 2 .
0 2 2 1 .
0 2 1 1 1
0 2 2 1 .
0 2 1 1 .
0 2 2 1 1
0 2 1 2 .
0 2 2 1 .
0 2 2 2 .
0 2 1 2 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 2 .
0 2 1 1 .
0 2 2 1 .
0 2 2 2 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 0
0 2 1 1 .
0 2 2 1 .
0 2 1 2 0
. 2 1 2 0
0 2 1 1 .
0 2 1 2 .
0 2 1 1 .
0 2 2 1 0
0 2 2 1 .
0 2 1 1 .
0 2 1 2 0
0 2 2 1 .
0 2 2 1 0
0 2 1 1 .
0 2 1 1 .
0 2 1 1 1
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 1
0 2 2 1 .
0 2 1 1 .
0 2 1 1 0
0 2 2 1 1
0 2 1 1 .
0 2 2 1 .
0 2 2 1 1
0 2 1 2 0
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 1
0 2 1 1 .
0 2 1 1 0
0 2 1 1 1
0 2 2 2 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 1
0 2 2 1 .
0 2 1 1 .
0 2 1 2 .
0 2 2 1 0
0 2 1 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 1
0 2 2 1 .
0 2 2 1 1
0 2 2 2 0
0 2 1 1 0
0 2 1 2 1
0 2 2 1 .
0 2 1 1 .
0 2 1 2 0
0 1 1 2 .
0 1 2 2 .
. 1 2 1 .
0 1 1 1 1
0 1 1 1 0
1 1 2 1 1
. 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 .
0 1 1 2 .
0 1 1 2 .
0 1 1 1 0
0 1 1 1 .
0 1 2 1 .
0 1 1 1 0
0 1 2 1 .
0 1 1 1 0
0 1 2 1 .
0 1 1 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 0
0 1 2 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 2 1
0 1 2 1 .
0 1 1 2 0
0 1 2 1 .
0 1 2 1 .
0 1 1 2 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 0
0 1 1 1 .
0 1 1 2 .
0 1 2 1 .
0 1 1 2 0
0 1 2 1 0
0 1 2 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 .
0 1 1 1 .
0 1 1 1 .
0 1 1 1 .
0 1 2 1 .
0 1 2 1 .
0 1 2 1 0
0 1 1 1 .
0 1 1 1 1
0 1 1 1 0
0 1 1 1 .
0 1 1 1 .
0 2 1 1 .
0 2 2 1 0
0 2 1 2 .
0 2 2 1 0
0 2 2 1 .
0 2 1 1 0
0 2 1 1 .
0 2 1 2 1
0 2 2 2 .
0 2 1 1 1
0 2 1 1 0
0 2 1 1 0
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 1
0 2 2 2 .
0 2 2 1 .
0 2 1 1 0
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 2 1 0
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 .
0 2 1 1 0
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 0
0 2 1 1 .
0 2 2 1 .
0 2 1 2 .
. 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 1 1 1
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 1
0 2 1 1 .
0 2 1 1 .
0 2 2 1 0
0 2 1 2 0
0 2 2 2 .
0 2 2 1 .
0 2 1 2 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 2 1 .
0 2 1 1 .
0 2 1 1 .
end
label values wcobs wcobs
label def wcobs 0 "Normal", modify
label def wcobs 1 "Overweight", modify
label values area area
label def area 1 "rural", modify
label def area 2 "urban", modify
label values q102 q102
label def q102 1 "male", modify
label def q102 2 "female", modify
label values q116 q116
label def q116 1 "yes", modify
label def q116 2 "no", modify
label def q116 8 "don't know", modify



where 'wcobs' is abdominal-obesity. 'area' has two values rural and urban. q102 is gender, and vdd is overweight status

if we tab wcobs

Code:
. ta wcobs
. ta wcobs
RECODE of
z_wc
(Z-score
Waist
circumferen
ce) Freq. Percent Cum.
Normal 794 99.62 99.62
Overweight 3 0.38 100.00
Total 797 100.00
Now we can see there are three children (cases ) with abdominal obesity and 794 are normal (controls)

I want to find out 3 children from the controls (794) which have same characteristics as the cases.

For example the first child with abdominal obesity is from urban area (area = 2), is a male (q102 = 1), his mother is not educated (q116 = 2) and he is not overweight (vdd = 0).
Now i want a child from the 794 cases who have the same characteristic.

Similarly for the second and third child.

This is just for example. my dataset is very big and i want to compare two groups while controlling for the background variables. Regression is not working because the disease is rare and I have very small number of cases (n = 243) and large number of controls (n = 92000) . Though i can find the controls manually by matching but it will take a lot of time.

Thanks for your help in advance.