lab7 - Analysis of Variance Allows us to test the...

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1 Analysis of Variance • Allows us to test the difference in means for more than two groups. – Tedious to do multiple t -tests – Increase your alpha error, even if you think you are keeping it at .05 (or whatever level you initially choose) • Null and alternative hypotheses 0 1 3 2 1 0 : : H H H k not µ L = = = Use the F statistic to test for the difference in means • Why use a ratio of variances to test for a difference in means ? – Sources of variance Between Groups : If you have multiple groups, each will have its own mean, and there will be an overall (grand) mean as well. – Each of the group means will differ from the grand mean, leading to a positive variance of group means from the grand mean Within Groups : Individual scores will vary from their particular group mean – If the variance of the group means from the grand mean is much bigger than the individual variance, then you have evidence that there are differences in group means.
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This note was uploaded on 07/17/2008 for the course PHYS 321 taught by Professor Zandt during the Spring '05 term at Ohio State.

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lab7 - Analysis of Variance Allows us to test the...

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