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.

Zusammenfassung Gerade bei Umfragen mit sog. sensitiven Variablen, wie etwa dem Einkommen, ist bekannt, daß z. B. die Bezieher sehr hoher Einkommen eher zur Verweigerung der Beantwortung von Einkommensfragen neigen als andere. Einfaches Vernachlässigen der unvollständigen Datensätze für die...

When some observations in the sample data are missing, the application of the regression method is considered for the estimation of population mean with and without the use of imputation. The performance properties of the estimators based on the methods of mean imputation, regression imputation...

We consider maximum likelihood (ML) estimation of mean and covariance structure models when data are missing. Expectation maximization (EM), generalized expectation maximization (GEM), Fletcher-Powell, and Fisher-scoring algorithms are described for parameter estimation. It is shown how the...