- I can address a couple of concrete points -
On Sat, 25 Mar 2000 15:22:43 GMT, Gene Gallagher
<[EMAIL PROTECTED]> wrote:
< snip >
> The real problem that we often see is a dataset composed of lots of zeros
> with a few positive values. From the literature, especially Hollander &
> Wolfe, I
Gene Gallagher wrote:
> The real problem that we often see is a dataset composed of lots of zeros
> with a few positive values. From the literature, especially Hollander &
> Wolfe, I know that a high percentage of ties poses problems for procedures
> based on ranks (even with the ties procedures).
Thank you for your thoughtful comments. I'm using Ramsey & Schafer's (R&S)
"Statistical Sleuth" as a text for my grad environmental stats class. They do
a very good job of presenting methods for analyzing outliers and the skewness
of the distribution(s) prior to using the t test or ANOVA. R & S do
On Fri, 24 Mar 2000 02:15:52 GMT, Gene Gallagher
< snip, good summary of some issues >
> SO, my question is "What is the current thinking on the robustness of
> the Kruskal-Wallis test for testing groups with very different
> variances?" Is Underwood right in his assessment that the nonparametr
On 24 Mar 2000, Bernard Higgins wrote:
> These are my thoughts:
>
> The sampling distribution of a test statistic is determined by the
> null hypothesis. So analysis of variance is used to test that a
> number of samples come from an identical Normal distribution
> against the alternative that
Hi Gene
> I'd just finished telling my class that when the assumption of
> homogeneity of variances is violated, use the Kruskal-Wallis test
> instead of the parametric equivalent.
> One student pointed out to me afterwards that Underwood (1997, p. 131,
> Experiments in Ecology) states that the
I'd just finished telling my class that when the assumption of
homogeneity of variances is violated, use the Kruskal-Wallis test
instead of the parametric equivalent.
One student pointed out to me afterwards that Underwood (1997, p. 131,
Experiments in Ecology) states that the K-W test also assume
