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Hi there I am using for the first time Mlwin and I need to fit a linear growth model to my data (i am also a beginner in this kind of analysis).
We are interested to analyse the variation between 3 time points (3 follow-ups) of alcohol use in our patients, in order to determine if we can predict relapse.
I manage to fit the basic model with 2 level (L1 follow-ups L2 subjects, as my variables change only between subjects) but when I add new terms in the model I get an error saying that my explanatory variables are different lengths(offs), which is true, they are different lengths.
So any advice on what should I do next?
Please help as I ma really stock!
MANY THANKS!!!

Could you provide some further information on why the explanatory variables are not the same length? If you imagine the columns of data used in the model as being placed next to each other to form a rectangle then MLwiN expects each row of data to correspond with a level-1 unit in your model.