Testing the Equality of Multi-Variances-ECO6416

Testing the Equality of Multi-Variances-ECO6416 - Testing...

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Testing the Equality of Multi-Variances The equality of variances across populations is called homogeneity of variances or homoscedasticity. Some statistical tests, such as testing equality of the means by the t-test and ANOVA, assume that the data come from populations that have the same variance, even if the test rejects the null hypothesis of equality of population means. If this condition of homogeneity of variance is not met, the statistical test results may not be valid. Heteroscedasticity refers to lack of homogeneity of variances. Bartlett's Test is used to test if k samples have equal variances. It compares the Geometric Mean of the group variances to the arithmetic mean; therefore, it is a Chi-square statistic with (k-1) degrees of freedom, where k is the number of categories in the independent variable. The test is sensitive to departures from normality. The sample sizes do not have to be equal but each must be at least 6.
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This note was uploaded on 10/07/2011 for the course ECO 6416 taught by Professor Staff during the Spring '08 term at University of Central Florida.

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Testing the Equality of Multi-Variances-ECO6416 - Testing...

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