Statistics Workbook For Dummies with Online Practice, 2nd Edition

Chapter 14

Taking the Guesswork Out of p-Values and Type I and II Errors

IN THIS CHAPTER

Sizing up a p-value measurement

Finding p-values

Examining p-values

Keeping Type I and Type II errors straight

So you’ve battled your way through hypothesis testing: null and alternative hypotheses, test statistics, critical values, rejecting or not rejecting Ho, and all that. You feel you finally have it all figured out when, suddenly, out of nowhere comes this thing called a p-value, and it rocks your world. Not to worry! This chapter helps you set the boat upright again for smooth sailing. This chapter helps you after you find your test statistics (see Chapter 11) and you want to make your conclusions correctly by using p-values. It also helps you interpret p-values that you see on homework, exams, or in the real world. (Did I say exams are the real world?)

Just a quick review before you start. Every hypothesis test has two hypotheses: the null hypothesis, Ho, and the alternative hypothesis, Ha. You cannot go against Ho unless you have sufficient evidence to provide reasonable doubt for Ho ...