Overview: T-tests are the perhaps one of the most simple types of statistical tests. The goal here is simply determining if one mean is statistically different than another mean. When to use an independent samples t-test: You perform an independent samples t-test (also known as a between subjects t-test) when comparing two continuous, unpaired means....Read More

Mediation and Moderation are often confused topics. Here, I’ll talk about the differences between the two and what they’re statistically testing. Put simply: Moderation attempts to show that a variable changes the relationship between X and Y. Mediation attempts to show that a variable is the channel through which X influences Y.​ Moderation Moderate is just a fancy word for “changed” or...Read More

The new deadly sins When researchers have wiggle room that allows them to snoop or fish around with their methods and data, their results don’t hold water. This extra flexibility allows folks to fish around until they find the methods/data analysis that gives the desired results. For example, researchers may make outcome-friendly decisions with questions...Read More

Overview The within-subjects (or repeated measures or paired-samples) t-test is a very common statistical method used to compare mean differences between two dependent groups. This is different than the between-subjects t-test because individuals are in both of the two comparison groups. For example, math achievement of students before and after an intervention. If the same...Read More

When to use a chi-square test: ​A chi square analysis is used when we have a categorical dependent and independent variable. Basically, we’re going to compute a cross-tabulation to ask if there’s a greater frequency of some kind of outcome event in group A compared to group B. Assumptions of the chi-square test: ​1. The...Read More