Nonresponse is a significant matter that cannot be denied in a sample survey. Declining response rates lead to increasing nonresponse bias which affects the estimated bias. Nonresponse adjustment can be used to deal with unit nonresponse by using nonresponse weight. Two possible models in which missingness in an ancillary database may be correlated with missingness in a survey are considered in this study for estimating the population mean when nonresponse occurs on both the study and auxiliary variables. Two auxi…