Hello,

I have 168 cases and 860 controls and 211 missing data. I have done a 2:1 matching for cases and controls. I have then reshaped the data using the following code:

Code:
 
 ds *_ctrl, not uniqueid      c1dage      variables etc . local vbles `r(varlist)'  . rename (`vbles') =_case  . gen long obs_num = _n  . clonevar group_id = uniqueid_case  . reshape long  `vbles', i(obs_num) j(cc) string (note: j = _case _ctrl) (note: cdgender_ctrl not found) (note: c1dage_ctrl not found) (note: c1dage_U_ctrl not found)  Data                               wide   ->   long ----------------------------------------------------------------------------- Number of obs.                      758   ->    1516 Number of variables                  49   ->      28 j variable (2 values)                     ->   cc xij variables:             uniqueid_case uniqueid_ctrl   ->   uniqueid                      c1dage_U_case c1dage_U_ctrl   ->   c1dage_U other variables etc -----------------------------------------------------------------------------  . drop obs_num  . duplicates drop if cc == "_case"  Duplicates in terms of all variables  (2 observations deleted)
Followed by:
Code:
replace cc = "1" if cc == "_case" replace cc = "0" if cc == "_ctrl" destring cc, replace
I now have
Code:
tab cc           cc |      Freq.     Percent        Cum. ------------+-----------------------------------           0 |        758       50.07       50.07           1 |        756       49.93      100.00 ------------+-----------------------------------       Total |      1,514      100.00
Have done clogit as follows:
Code:
 clogit cc i.smoke area*, group( group_id ) iterate(1) note: multiple positive outcomes within groups encountered. note: 228 groups (407 obs) dropped because of all positive or       all negative outcomes.  Iteration 0:   log likelihood = -226.34064   Iteration 1:   log likelihood = -225.14419   convergence not achieved  Conditional (fixed-effects) logistic regression                                                  Number of obs     =        551                                                 LR chi2(2)        =      23.23                                                 Prob > chi2       =     0.0000 Log likelihood = -225.14419                     Pseudo R2         =     0.0491  ------------------------------------------------------------------------------           cc |      Coef.   Std. Err.      z    P>|z|     [95% Conf. Interval] -------------+----------------------------------------------------------------         smoke|         Yes  |   2.106454   .5176006     4.07   0.000     1.091976    3.120933         area |   .0005998   .0005461     1.10   0.272    -.0004706    .0016702 ------------------------------------------------------------------------------ Warning: convergence not achieved
Not entirely sure that this is correct. Then when I try and add in code to get odds ratios, the data completely changes as follows:
Code:
  clogit cc i.smoke area*, group( group_id ) iterate(1) or note: multiple positive outcomes within groups encountered. note: 228 groups (407 obs) dropped because of all positive or       all negative outcomes.  Iteration 0:   log likelihood = -226.34064   Iteration 1:   log likelihood = -225.14419   convergence not achieved  Conditional (fixed-effects) logistic regression                                                  Number of obs     =        551                                                 LR chi2(2)        =      23.23                                                 Prob > chi2       =     0.0000 Log likelihood = -225.14419                     Pseudo R2         =     0.0491  ------------------------------------------------------------------------------           cc | Odds Ratio   Std. Err.      z    P>|z|     [95% Conf. Interval] -------------+----------------------------------------------------------------        smoke |         Yes  |   8.219045   4.254183     4.07   0.000     2.980156    22.66751         area |     1.0006   .0005465     1.10   0.272     .9995295    1.001672 ------------------------------------------------------------------------------ Warning: convergence not achieved
Help?