Improvement on the non-response in the population ratio of mean for current occasion in sampling on two occasions

In this article,we attempt the problem of estimation of the population ratio of mean in mail surveys. this problem is conducted for current occasion in the context of sampling on two occasions when there is nonresponse (i) on both occasions,(ii) only on the first occasion and (iii) only on the second occasion. we obtain the gain in efficiency of all the estimators over the direct estimate using no information gathered on the first occasion. we derive the sample sizes and the saving in cost for all the estimators,which have the same precision than the direct estimate using no information gathered on the first occasion. an empirical study that allows us to investigate the performance of the proposed strategy is carried out.