# 10.10: Chapter Key Terms

Cohen’s d
a measure of effect size based on the differences between two means. If $$d$$ is between 0 and 0.2 then the effect is small. If $$d$$ approaches is 0.5, then the effect is medium, and if $$d$$ approaches 0.8, then it is a large effect.
Independent Groups
two samples that are selected from two populations, and the values from one population are not related in any way to the values from the other population.
Matched Pairs
two samples that are dependent. Differences between a before and after scenario are tested by testing one population mean of differences.
Pooled Variance
a weighted average of two variances that can then be used when calculating standard error.