Greetings
I'll be grateful for hints on the following, which has arisen in the
course of a student project using real data from her industrial
placement. The samples are large and the distributions reasonably
normal.
She wants to test differences between the means of several groups, but
the group SDs vary considerably - much more than the means and without
any clear pattern, along the following (simplified) lines:
A mean 10.2 SD 2.0
B mean 11.5 SD 0.4
C mean 10.4 SD 0.6
D mean 10.9 SD 4.5
E mean 10.7 SD 3.0
Obviously she cannot use standard ANOVA, which requires equal variances,
nor is any transformation available to stabilise the variances.
Please reply to me, not to Allstat, and I'll summarise if appropriate.
Many thanks DFG
-----------------------------
David Goda
SCIT, Univ. of Wolverhampton Phone (01902)321444
Wulfruna Street Email [log in to unmask]
Wolverhampton WV1 1SB
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