effect size

(NL: effectgrootte)

The effect size is a measure that expresses the strength of an association between two variables.

Depending on the context, and more specifically on the measurement levels of the variables, there are different methods to define an effect size.

• Cramer's V is a measure for the strength of the association between two qualitative variables.

• Cohen's d is a measure for the difference (of the mean) between two groups.

• Pearson's correlation coefficient is a measure for the strength of a linear association between two quantitative variables.

In addition to these, there are dozens of definitions of effect sizes, each with their own scope and interpretation.

Effect sizes are complementary to hypothesis testing. A hypothesis test determines whether an association is statistically significant, while an effect size indicates how strong that association is.