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Unformatted text preview: A Type I error is often represented by the Greek letter alpha ( ) and a Type II error by the Greek α letter beta ( β ) . In choosing a level of probability for a test, you are actually deciding how much you want to risk committing a Type I error—rejecting the null hypothesis when it is, in fact, true. For this reason, the area in the region of rejection is sometimes called the alpha level because it represents the likelihood of committing a Type I error. In order to graphically depict a Type II, or , error, it is necessary to imagine next to the distribution β for the null hypothesis a second distribution for the true alternative (see Figure 1). If the alternative hypothesis is actually true, but you fail to reject the null hypothesis for all values of the test statistic falling to the left of the critical value, then the area of the curve of the alternative (true) hypothesis...
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This note was uploaded on 11/15/2011 for the course QMST 2333 taught by Professor Mendez during the Fall '08 term at Texas State.
- Fall '08