A note on the optimum allocation of resources to follow up unit nonrespondents in probability

Common practice to address nonresponse in probability surveys in National Statistical Offices is to follow up every nonrespondent with a view to lifting response rates. As response rate is an insufficient indicator of data quality, it is argued that one should follow up nonrespondents with a view to reducing the mean squared error (MSE) of the estimator of the variable of interest. In this paper, we propose a method to allocate the nonresponse follow-up resources in such a way as to minimise the MSE under a quasi-randomisation framework. An example to illustrate the method using the 2018/19 Rural Environment and Agricultural Commodities Survey from the Australian Bureau of Statistics is provided.