## ← Types of Effect-Size Measures - Intro to Inferential Statistics

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Showing Revision 6 created 05/24/2016 by Udacity Robot.

1. Now are there many types of effect size measures? I can think of at least six
2. or seven right now. But most of them fall under two main groups. Two families,
3. if you will. The first we call difference measures. The easiest difference
4. measure is one we've already talked about, the mean difference. The next type
5. are called standardized differences. And there are several different types of
6. standardized differences measures. But we'll focus on one, and that measure's
7. called Cohen's d. This is the standardized difference measure we're going to
8. use throughout the rest of this course. Notice that Cohen's d as a standardized
9. difference measure actually tells us about the mean difference. It does so in
10. standard deviation units. The next family are called correlation measures.
11. There are again, several different correlation measures, as with standardized
12. mean differences. We're going to focus on one, which is called r squared. R
13. squared tells us to proportion or percentage a variation in one variable. In
14. other words, change in one variable, that is related to another variable, and
15. sometimes, we say instead of related to, we say explained by. What we mean,
16. explained by, is that we can explain a certain percentage or proportion of
17. variation or change in one variable by knowing the value of the other variable.