We consider the integration of the non-probability sample into the Statistical survey on population by ethnicity, native language and religion of the Lithuanian census 2021. The propensity score adjustment is used to correct the bias of estimates of parameters based on the non-probability sample. We apply a parametric model to describe the response mechanism that is assumed to be not missing at random. Calibration and maximum likelihood based methods are used to estimate the propensity scores. We compare the results with those obtained under the missing at random assumption in a simulation study carried out using census data.
