Question

A student conducts a research project to test the effect of an independent variable with two conditions. The value for Cohen's d for her data is 0.25. Based on this, she concludes that the independent variable had _________ effect on the dependent variable.

Answer 1

Cohen's d is a parameter which tests the effect size for difference between two means. A value of d = 0.20 implies a 'small' effect size, and a value of 0.5 suggests a medium effect size.

So if for a test you get a d value which is less than 0.2, then the difference you see in two groups' means is just trivial and nothing more, even if it is a statistically significant result.

In this case we have d = 0.25, so the independent variable had small effect size on the dependent variable.