Eric Bohlman <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> [EMAIL PROTECTED] (mac55) wrote in
> news:[EMAIL PROTECTED]:
>
> > A simple question......
> >
> > If you are comparing binary data from two groups with underlying
> > populations that are normal.....I assume you can use a two sample Z
> > test for binomial proportions or a chi squared test on a 2x2
> > contingency table.
> >
> > What happens if the underlying populations aren't normal? I know
> > the Z test is out. Can you still employ the chi squared distribution.
> > If not, what non-parametric test could you use?
>
> Nothing in the logic of either test requires the assumption that the data
> be derived by dichotomizing a normal continuous variable. The Z test only
> requires that the number of cases be large enough that the normal
> approximation to the binomial is decent.
You are correct. Let's say the data are skewed or that the
numbers aren't large enough for the normal approximation? Is Chi
squared a valid test?
mac
.
.
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