I am having trouble with where to start with organizing and analyzing my data. I have a variable called stai_score which is the level of anxiety for subjects. This score is numerical ranging from 20-80 and is recorded at 3 time points (baseline, week 4 and week 8). I am trying to create a new variable called change. This variable is a categorical variable that measures a success as "a change in stai_score greater than or equal to 3 from baseline to week 8" and a failure as "a change in stai_score less than 3 from baseline to week 8".
I am struggling in how to put in code that will create this new vector "change" because of the two timepoints. Any ideas?