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An analysis of variance differs from a t test for independent means in that an analysis of variance?
Analysis of Variance (ANOVA) compares 3 or more means. The t-test would only compare 2 means.
When the null hypothesis is true the ratio of the between groups population variance estimate to the within groups population variance estimate should be about?
1
Does standard deviation effect the alpha level?
Yes.For some tests, such as the Fisher F-test, the test statistic is an estimate of the variance. If the alpha level was not affected, the test would be no use at all!Yes.For some tests, such as the Fisher F-test, the test statistic is an estimate of the variance. If the alpha level was not affected, the test would be no use at all!Yes.For some tests, such as the Fisher F-test, the test statistic is an estimate of the variance. If the alpha level was not affected, the test would be no use at all!Yes.For some tests, such as the Fisher F-test, the test statistic is an estimate of the variance. If the alpha level was not affected, the test would be no use at all!
Why is variance important when using statistics?
Variance is basically the raw material of statistics. If you don't have variance (differences in scores) you don't have much to work with or for that matter you don't have much to talk or think about. Consider a test where everyone gets the same score. What does that tell you? You might have some measurement problem, wherein the test is so easy everyone aces it. Still it might be so hard that everyone gets a zero. Now consider two tests. On each everyone gets the same score. That is on test one everyone gets a 15 and on the second test everyone gets a 10. That isn't telling you much is it? Now these are extreme cases, but in general, more variance is better and less variance isn't so good.
When do you run a post-hoc test?
You run a post-hoc test after conducting an analysis of variance (ANOVA) and finding a significant result. A post-hoc test is used to determine which specific groups differ significantly from each other, as ANOVA only tells you that there is a difference somewhere but not which groups are different.
