We introduce a novel method of sensitivity analysis to aid in assessing the missing-at-random assumption in a two-way contingency table with one supplemental margin. The procedure involves a set of response odds and nonresponse odds computed from the observed counts.

We establish a sufficient condition for the occurrence of nonresponse boundary solutions in a two-way square contingency table with nonignorable nonresponse. The condition depends only on the observed counts and thus it does not require computing the maximum likelihood estimates.