  This paper shows how to manage null entries in pairwise comparisons matrices.
Although assessments can be imprecise, since subjective criteria are involved,
the classical pairwise comparisons theory expects all of them to be available.
In practice, some experts may not be able (or available) to provide all
assessments. Therefore managing null entries is a necessary extension of the
pairwise comparisons method. It is shown that certain null entries can be
recovered on the basis of the transitivity property which each pairwise
comparisons matrix is expected to satisfy.
