Hello. I've been struggling with question b. help needed . The following data sets contain BMI measurements for the baseline, 3 months, and 9 months, for the intervention and control group patients.   data int; input ID$ GROUP$ BMI_base BMI_3mos BMI_9mos; cards; 101         int          34.5 33.8 31.1 102         int          30.7 29.6 27.3 103         int          32.0 30.7 27.5 105         int          34.6 33.5 33.3 106         int          37.6 34.9 30.1 107         int          30.2 29.2 28.7 108         int          37.2 36.0 35.1 109         int          35.2 33.3 33.7 111         int          32.3 31.4 29.4 ;   data cnt; input ID$ GROUP$ BMI_base BMI_3mos BMI_9mos; cards; 401         cnt          33.7 33.4 33.2 402         cnt          31.2 30.1 29.8 404         cnt          30.8 31.1 31.8 406         cnt          29.2 29.0 28.9 408         cnt          27.7 27.3 27.9 409         cnt          33.8 32.9 31.4     a) Concatenate the data sets and compute the change in BMI between the baseline and 9 months. Your output should look like this. Obs ID GROUP BMI_base BMI_3mos BMI_9mos BMI_change 1 101 int 34.5 33.8 31.1 -3.4 2 102 int 30.7 29.6 27.3 -3.4 3 103 int 32.0 30.7 27.5 -4.5 4 105 int 34.6 33.5 33.3 -1.3 5 106 int 37.6 34.9 30.1 -7.5 6 107 int 30.2 29.2 28.7 -1.5 7 108 int 37.2 36.0 35.1 -2.1 8 109 int 35.2 33.3 33.7 -1.5 9 111 int 32.3 31.4 29.4 -2.9 10 401 cnt 33.7 33.4 33.2 -0.5 11 402 cnt 31.2 30.1 29.8 -1.4 12 404 cnt 30.8 31.1 31.8 1.0 13 406 cnt 29.2 29.0 28.9 -0.3 14 408 cnt 27.7 27.3 27.9 0.2 15 409 cnt 33.8 32.9 31.4 -2.4   b) Remove the intervention group patients whose BMI decreased by less than 3 points and also the control group patients whose BMI increased over time. Your output should look like this: Obs ID GROUP BMI_base BMI_3mos BMI_9mos 1 101 int 34.5 33.8 31.1 2 102 int 30.7 29.6 27.3 3 103 int 32.0 30.7 27.5 4 106 int 37.6 34.9 30.1 5 401 cnt 33.7 33.4 33.2 6 402 cnt 31.2 30.1 29.8 7 406 cnt 29.2 29.0 28.9 8 409 cnt 33.8 32.9 31.4 ... View more