Universidad de L a HabanaThe eNect of assuming an inadequate superpopulation model in stratifed sampling is studied when a shrinkage technique is used. The robustness is close related with the balance of the strata samples. This theoretical problem is present in studies of ecology. The results obtained enable to estimate the abundance of plankton when salinity is the auxiliary variable and expert's advise, in coast experimental stations networks, is used for fixing the superpopulation model
The existence of missing observations when the difference of means is estimated determines the need of sub sampling among the non respondents. Ranked set sampling is used for sub sampling. The information provided on one of the variables by the non respondents at the first attempt permits to rank them. The behavior of a ranked set sampling model with respect to other alternattives is studied in this paper. An unbiased estimator is derived and its expected variance is obtained. The proposed model is compared with the use of simple random sampling and Two‐phase sampling for stratification.
This paper is devoted to the study of the behavior of the use of double sampling for dealing with nonresponses, when ranked set sample is used. The characteristics of the sampling strategies are derived. The structure of the errors generated the need of studying of the optimality of the strategies by performing a set Monte Carlo experiments.
Abstract:In this study we deal with the estimation of the population ratio, when a Randomized Response (RR) procedure is used for collecting responses and Ranked Set Sampling (RSS) is the selection method. The variances of the suggested estimators are calculated. Comparisons between different estimators are presented.
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