Determines if contrasts are estimable, that is, if the contrasts can be written as a linear function of the data.
A basis for a null space (can be found with
Consider the setting E(Y)=Xb. A linear function of b,
say l'b is estimable if and only if there exists an r such
that r'X=l' or equivalently l=X'r. Hence l must be in
the column space of X', i.e. in the orthogonal complement of the
null space of X. Hence, with a basis B for the null space,
is_estimable() checks if each row l of the matrix K is
perpendicular to each column basis vector in B.
A logical vector.
S<c3><b8>ren H<c3><b8>jsgaard, [email protected]
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