Hello! I am a student and new to Mplus so I sincerely apologize if I'm not making sense.
I have 3 waves of longitudinal data spaced 2-years apart. My outcome is a continuous variable of the number of functional limitations for each respondent.
I was originally using DATA TWOPART to examine trajectories over time. However, now my advisor is asking me to do age trajectories (my respondents are between 50 and 85 years old). I have tried creating variables: age1 age2 age3 for the age of each respondent during each wave. However, looking through the Mplus documentation I'm wondering if I should be doing a cohort analysis?
It sounds like your time variable should be age rather than measurement occasion (1, 2, 3). Check our short course video and handout for Topic 3, slides 128 - on our website describing Tscores (corresponding to your age1, age2, age3 variables). Multiple cohorts can be useful if you have only a few different ages (or age grps) at the starting point.