Unformatted text preview: One- and Two-Tailed Tests In the previous example, you tested a research hypothesis that predicted not only that the sample mean would be different from the population mean but that it would be different in a specific direction —it would be lower. This test is called a directional or one-tailed test because the region of rejection is entirely within one tail of the distribution. Some hypotheses predict only that one value will be different from another, without additionally predicting which will be higher. The test of such a hypothesis is nondirectional or two-tailed because an extreme test statistic in either tail of the distribution (positive or negative) will lead to the rejection of the null hypothesis of no difference. Suppose that you suspect that a particular class's performance on a proficiency test is not representative of those people who have taken the test. The national mean score on the test is 74.representative of those people who have taken the test....
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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