Stratified random sampling at differential rates is commonly used in social science surveys to improve the chances of getting sufficiently large samples of subpopulations of interest. Multi-phase sampling is often used to further target desired populations. The variances of such samples can be estimated using jackknifing, which creates replicated values of the characteristic of interest as if o...

Background: Up to one third of early stage prostate cancer patients who underwent radical prostatectomy experienced disease progression. Different controls sampling methods applied in nested case-control studies, which searched for biomarkers that provide prognostic information and help understand disease progression mechanisms, have been adopted by researchers in different studies. Aims: Throu...

understanding people’s ecological behaviors and the impacts of human activities on natural environment is one of the most important concepts in ecological psychology research. the purpose of this study was to investigate causal relationship between factors and maize growers’ ecological behavior concerning the application of external inputs such as water, fertilizers, chemical pesticides, and ma...

this article studies the staff satisfaction from the performance of public relation section and its factor affecting in gas company of the city of mashhad in khorasan razavi province. the study has been conducted via survey method and data gathered through standard questionnaires. 375 people of total 955 staffs in the company were selected as sample size using proportionate stratified random sa...

Methodology: It was cross-sectional study conducted in randomly selected higher secondary college in rural area from Western Maharashtra, during September 2012 to October 2012. The calculated sample size for the study was 121. The sampling technique used was stratified ramdom sampling. A self administered questionnaire was used for data collection. Analysis was done using percentage and chi – s...

Prentice & Pyke (1979) established that the maximum likelihood estimate of an odds ratio in a case-control study is the same as would be found by fitting a logistic regression; in other words, for this specific target the incorrect prospective model is inferentially equivalent to the correct retrospective model. Similar results have been obtained for other models, and conditions have also been ...

In this paper, for the Stratified Median Ranked Set Sampling (SMRSS), proposed by Ibrahim et al. (2010), we examine the proportional and optimum sample allocations that are two well-known methods for sample allocation in stratified sampling. We show that the variances of the mean estimators of a symmetric population in SMRSS using optimum and proportional allocations to strata are smaller than ...

Software reliability testing provided the necessary guarantee for improving software reliability level and estimation. The traditional method for generating software reliability test cases could be seen as a simple random sampling, which was randomly choosen according to the operational profile defined by Musa. The stratified sampling was well known as a complex but more accurate sampling appro...

T paper describes, analyzes and evaluates an algorithm for estimating portfolio loss probabilities using Monte Carlo simulation. Obtaining accurate estimates of such loss probabilities is essential to calculating value-at-risk, which is a quantile of the loss distribution. The method employs a quadratic (’’delta-gamma’’) approximation to the change in portfolio value to guide the selection of e...