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Unformatted text preview: A OneWay Analysis of Variance is a way to test the equality of three or more means at one time by using variances. Assumptions • The populations from which the samples were obtained must be normally or approximately normally distributed. • The samples must be independent. • The variances of the populations must be equal. Hypotheses The null hypothesis will be that all population means are equal, the alternative hypothesis is that at least one mean is different. In the following, lower case letters apply to the individual samples and capital letters apply to the entire set collectively. That is, n is one of many sample sizes, but N is the total sample size. Grand Mean The grand mean of a set of samples is the total of all the data values divided by the total sample size. This requires that you have all of the sample data available to you, which is usually the case, but not always. It turns out that all that is necessary to find perform a oneway analysis of variance are the number of samples, the sample means, the sample variances, and the sample sizes. Another way to find the grand mean is to find the weighted average of the sample means. The weight applied is the sample size....
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This document was uploaded on 04/03/2012.
 Spring '09
 Variance

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