I would like to estimate a Multiple Cohort Growth Model similar to the example in ch 6.18 of the user guide. Instead of cohorts based on birth year, my three cohorts are grouped according to grade at baseline – 3rd, 6th, and 9th grade.
So ages within each cohort do range at each assessment (each cohort was assessed at three timepoints – 18 months apart). Can I use the syntax from 6.18 as-is or are there any adjustments I need to make to how my data is structured or to the syntax?
Below is a draft of my syntax, thanks! Note: APD is the outcome whose trajectory I want to model.
GROUPING = g (1 = 3RD 2 = 6TH 3 = 9TH ); MODEL: i s |APD1@0APD2@.15APD3@.3; [i] (1); [s] (2); i (3); s (4); i WITH s (5); APD1 ON age1; APD2 ON age2; APD3 ON age3 (g6); APD1-APD2; APD3 (v6); MODEL SIXTH: i s |y1@.3y2@.45y3@.6; APD1 ON age1 (g6); APD2 ON age2; APD3 ON age3 (g9); APD1 (v6); APD2; APD3 (v9); MODEL NINTH: i s |y1@.6y2@.75y3@.9; APD1 ON age1 (g9); APD2 ON age2; APD3 ON age3; APD1 (v9); APD2-APD3;