Hi all, I've spent a ton of time researching and I can't find a solution to my problem. I have two databases: 1) Survey collected at baseline and 2) Medical data collected at baseline and f/u with data in multiple rows per ID for different years the data was collected. I tried merging the two datasets by ID, but then the baseline survey doubled because it added the f/u data to the same lines. Any tips? - Rachel What I have Database#1 Survey data (only collected at baseline) ID VAR1 VAR2 1 1 2 2 3 2 3 3 1 Database#2 Medical record data (some ID's have both baseline and follow-up data for BMI, but on different rows) ID Baseline Followup BMI 1 1 0 23 1 0 1 24 2 0 1 20 2 1 0 19 3 1 0 30 I want my merged database to look like this: ID VAR1 VAR2 BMI_baseline BMI_fu BMI_change 1 1 2 23 24 +1 2 3 2 19 20 -1 3 3 1 30 . .
... View more