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We have done a cross-sectional survey of disease X in cattle. Seropositives were matched to seronegatives on region, village, farm, species, breed and age within 2 years. Now, we want to know the milk production (noted in questionnaire) (continuous independent variable) predicted by a model depending on test result (positive or negative), last calve months (continuous independent variable) and parity (number of times a cow has calved....1,2,3 etc) .............can we do a analysis keeping the matching pairs in mind.....
I have tried this command: xtmixed b_milk_kg i.elisa c_last_calve_months e_parity || c_village : || d_farm_id : || a_species :

BUT THIS NOT TAKE ACCOUNT THE MATCHING PAIRS.....
CAN U HELP