Here is an example of the data (there are more ppts, this is just the first 25 rows) Time= time in months from intervention. When I speak of centering, I would grand mean center the variable as follows (subtract the mean of TIME from TIME for each row): Time_Cent= TIME- Time_MEAN;: </> ID WEIGHT AGE GENDER TIME 25003 122.041 52 2 0 25003 122.002 52 2 5 25003 121.883 52 2 12 25001 121.762 56 3 0 25001 121.729 56 3 8 25001 121.691 56 3 12 25004 122.122 42 2 0 25004 122.051 42 2 7 25004 122.023 42 2 13 25009 121.79 66 1 0 25009 121.763 66 1 7 25009 . 66 1 . 25015 121.904 40 2 0 25015 . 40 2 . 25015 121.777 40 2 56 25026 121.909 56 2 0 25026 121.869 56 2 6 25026 121.843 56 2 12 25027 . 36 2 0 25027 . 36 2 . 25027 . 36 2 . 25048 121.619 48 2 0 25048 121.573 48 2 6 25048 121.568 48 2 12 25059 . 57 1 0 </>
... View more