abstract background: hypertension is the main risk factor of many diseases and the main reason of death all over the world. because the signs of hypertension are not clear, people do not feel its dangers and do not believe they are at risk. this problem makes preventing hypertension a great challenge for the health system. one factor that is related to lifestyle and is effective in preventing h...

Population stratification (PS) is referred to the systematic difference in allele frequencies between subpopulations in a population. It could cause a false-positive conclusion in a case-control association study, where the association is due to the structure of the underlying population, not a disease-associated locus. In this paper, we study the joint effects of PS and data sampling when the ...

The application of ranked set sampling (RSS) techniques to data from a dichotomous population is currently an active research topic, and it has been shown that balanced RSS leads to improvement in precision over simple random sampling (SRS) for estimation of a population proportion. Balanced RSS, however, is not in general optimal in terms of variance reduction for this setting. The objective o...

An almost unbiased estimator using known value of some population parameter(s) is proposed. Under simple random sampling without replacement (SRSWOR) scheme the expressions for bias and mean square error (MSE) are derived. Numerical illustrations are given.

Systematic sampling is a commonly used technique due to its simplicity and ease of implementation. The drawback of this simplicity is that it is not possible to estimate the design variance without bias. There are several ways to circumvent this problem. One method is to suppose that the variable of interest has a random order in the population, so the sample variance of simple random sampling ...

simple harmonizable processes (shp) introduced by soltani and parvardeh (2006) are a large class of nonstationary processes which includes stationary and periodically correlated (pc) processes. detection and estimation of shp structure are important problems when dealing with nonstationary data. in this paper, we study the spectral properties of simple processes and propose a method to detect a...