I am a little bit confused about type of model to apply because my type of data.
I am interesting in get regression parameters for time (dependent variable) with independent variables= sex + age+ var3+var4 (maybe patient) my data have multiple measures by patient.
My first idea was apply ols, but now I am reading about models with fixed effect and random effects (xtreg in stata) and maybe I thought that I should use a fixed effect model, one example of my data is below, data is unbalanced:
Time, Var3 and Var4 are continous.
Any suggestion I would appreciate
Thanks in advance: