Hello I am attempting to perform a two stage longitudinal analysis. My entire data set has two time points for each participant.
I understand that the subject order in the FSGD file should correspond with the QDEC file run through long_mris_slopes.

In my case the FSGD file has half as many inputs as the QDEC file.

My question is would I take the covariates from TP1 and TP2 and take the average to input into the FSGD file?

If that is the case is there anything wrong with performing the long_qdec_table --qdec "qdec.table.dat --cross --out "cross.qdec.table.dat" command and using that co-variate data to input into the FSGD file?

Respectfully,

-Tim