Survey Sampling – Introduction When it’s not feasible to study an entire target population, a simple random sample is the next best option; with sufficient sample size, it satisfies the assumption of independent and identically distributed variables. And perhaps even more important, it will tend to be nicely representative for the population with regard to […]
Summary How to draw one or many samples from your data in SPSS? This tutorial demonstrates some simple ways for doing so. We’ll point out some tips, tricks and pitfalls along the way. Let’s get started and create some test data by running the syntax below. SPSS Syntax for Creating Test Data *Create test data with […]
“I have 5 groups of 10 cases in my data. How can I draw a stratified random sample from these cases? That is, from groups 1 through 5 I’d like to draw exactly 5, 4, 5, 6 and 3 cases at random. What’s an efficient way to do this?” Before and after drawing our stratified […]
Introduction Popular statistical procedures such as ANOVA, a chi-square test or a t-test quietly rely on the assumption that your data are a simple random sample from your population. Violation of this assumption may result in biased or even nonsensical test results and few researchers seem to be aware of this. Plenty of reasons for a brief discussion of simple […]
