“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 […]
DO REPEAT is a command for running other commands repetitively.SPSS DO REPEAT is often used for looping over (possibly new) variables. VECTOR with LOOP is an alternative way for doing so. Introduction Suppose we have a variable containing values 1 through 4 and we’d like to dichotomize it for a regression analysis. (For some more background, see Creating Dummy Variables in SPSS.) […]
Independent Samples T-Test – What Is It? Null Hypothesis Test Statistic Assumptions Statistical Significance Effect Size Independent Samples T-Test – What Is It? An independent samples t-test evaluates if 2 populations have equal means on some variable.If the population means are really equal, then the sample means will probably differ a little bit but not […]
SPSS one-sample t-test tests if the mean of a single metric variable is equal to some hypothesized population value. The figure illustrates the basic idea. SPSS One Sample T-Test – Example A scientist from Greenpeace believes that herrings in the North Sea don’t grow as large as they used to. It’s well known that – on average – […]
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 […]
Independent Samples T-Test SPSS Independent Samples T-Test Independent Samples T-Test Other SPSS T-Test Tutorials SPSS Paired Samples T-Test SPSS One Sample T-Test T-Test Background Tutorials Z-Scores – What and Why? What is a Dichotomous Variable?
