Hello all,
Suppose there are two groups in a randomise analysis. At first you perform a t-test to look for a group effect. The design matrix looks like this:
1 0
1 0
1 0
1 0
0 1
0 1
0 1
0 1
As a next step, you add a covariate. E.g. age. The problem is that age is missing for some participants. What's the proper way to create a design matrix for a sparse dataset in randomise? For example, the age is known for all participants except for three. How should the third column look?
Thanks.
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