One-Way+ANOVA+Assumptions

One-Way ANOVA Assumptions (Analysis of Variance) (GWU EMSE-271)
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"The results of a one-way ANOVA can be considered reliable as long as the following assumptions are met:
 * Response variable must be normally distributed (or approximately normally distributed).
 * Samples are independent.
 * Variances of populations are equal.
 * Responses for a given group are independent and identically distributed normal random variables (not a simple random sample (SRS)).

ANOVA is a relatively robust procedure with respect to violations of the normality assumption. If data are ordinal, a non-parametric alternative to this test should be used such as Kruskal-Wallis one-way analysis of variance" - Wikipedia.

Assumptions:
 * 1) Error term normally distributed with a mean 0 and variance sigma squared.
 * Check with Normal Probabiliyt Plot
 * 1) Variance of error terms across treatments
 * Plot residuals of variances against each other
 * Or use Bartlett's test for equal variance

- EMSE 271,. Fall 2009, Slide 306


 * Sources:**
 * One-way ANOVA. (2009, November 13). In //Wikipedia, The Free Encyclopedia//. Retrieved 16:13, December 17, 2009, from []
 * EMSE 271, Fall 2009