These study tips are designed to clarify key points and help you to avoid errors that students commonly make. Review the Tips for Success as you study each chapter and review them again after you have studied each chapter.

1. It is very easy to get confused between a Type I error and a Type II error. Be sure you understand each type of error (and the difference between them) before moving onto the section on statistical power.
2. When figuring statistical power, it is very helpful to make a diagram of the two distributions (for an example, see Figure 8-6, p. 267).
3. Note that the formula for finding the predicted mean of Population 1 is a simple algebraic manipulation of the formula for finding effect size.
4. Be sure you understand why statistical power and beta can be thought of as opposites (and why beta = 1 - power, and power = 1 - beta)
• Power is the probability of getting a significant result if the research hypothesis is true, and beta is the probability of getting a nonsignificant result if the research hypothesis is true (that is, the probability of committing a Type II error).
5. As you will hopefully notice in this chapter, the topics of effect size, hypothesis testing decision errors, and statistical power are all closely linked. As much as possible, try to consider their commonalities when going through the chapter.

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