On Sat, 5 Feb 2000 16:46:38 -0000, "haytham siala" <[EMAIL PROTECTED]> wrote: > Is the homogoneity of variance-covariance prerequisite to ANOVA a > requirement? No, it is a warning that your model might be inappropriate, in any of several ways. A single EXTREME outlier could make any average meaningless, regardless of N. If your averages all seem useful, then the ANOVA is probably robust. If your groups have equal Ns, the tests are quite good in terms of comparing the means. > If yes, if my data failed the homogoneity of variance-covariance test, > should I use a non-parametric test instead or is ANOVA robust enough to be > conducted even if the data fails the homogoneity of variance-covariance > test? The proper response, if the failure is an important one, is to further review your assumptions. Which specific transformation or non-parametric test might test what you want to test? -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html =========================================================================== This list is open to everyone. Occasionally, people lacking respect for other members of the list send messages that are inappropriate or unrelated to the list's discussion topics. Please just delete the offensive email. For information concerning the list, please see the following web page: http://jse.stat.ncsu.edu/ ===========================================================================
