Message-ID: <200504281613.j3SGDqWm023295@meitner.gene.com>
Date: 2005-04-28T16:13:52Z
From: Bert Gunter
Subject: normality test
In-Reply-To: <4270DB1C.20301@vanderbilt.edu>
Below.
>
> Usually (but not always) doing tests of normality reflect a lack of
> understanding of the power of rank tests, and an assumption of high
> power for the tests (qq plots don't always help with that because of
> their subjectivity). When possible it's good to choose a
> robust method.
> Also, doing pre-testing for normality can affect the type I
> error of
> the overall analysis.
>
> --
> Frank E Harrell Jr
Also, qqplots or any other kind of screening for normality can affect the
type I error.
Indeed, one might ask what type I error means in such circumstances. :-)
Indeed, one might ask what hypothesis testing means in such circumstances.
Cheers,
Bert