On Mon, 5 Feb 2001, "June" <rjkim> wrote:
> Isn't a chi-square test inherently a 'one-sided sig. test'?
Not inherently. The common (most common?) application, in testing the
hypothesis of independence of classification systems in a two-way table
of frequencies, is a one-sided test, of course. But that's because of
the nature of the test itself, not because the reference distribution is
chi-square.
> I just read a paper claiming that it uses a 'one-sided' rather than
> 'two-sided' test. So it regards a chi-square value of 3.3 (df=1) is
> significant at the level of 0.05. (As you all know, the critical value
> of chi-square (df=1) at the alpha of 0.05 is 3.84.)
>
> I know this claim is simply erroneous.
Well, it may be. But since you haven't told us what hypothesis was being
tested, let alone whether the alternative hypothesis could logically have
been one-sided vs. two-sided, we cannot tell whether we agree with you
or not.
> But I am just wondering whether there can be any occasion one may use
> 'two-sided' test with the chi-square distribution.
The simplest case: testing the null hypothesis that a population
variance is equal to a specified value, against the alternative that
(1) the population variance is not equal to that value (two-sided);
(2) the population variance is less than that value (one-sided);
(3) the population variance is greater than that value (one-sided).
-- DFB.
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Donald F. Burrill [EMAIL PROTECTED]
348 Hyde Hall, Plymouth State College, [EMAIL PROTECTED]
MSC #29, Plymouth, NH 03264 (603) 535-2597
Department of Mathematics, Boston University [EMAIL PROTECTED]
111 Cummington Street, room 261, Boston, MA 02215 (617) 353-5288
184 Nashua Road, Bedford, NH 03110 (603) 471-7128
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