# [R] Hypothesis test

Moustafa ElHousinie drhosini at hotmail.com
Sat Apr 7 08:33:16 CEST 2001

```Dear colleague:

Actually that is what is done.

When using the z-test between proportions in two different groups, or using
chi-squared to test the null hypothesis of equal proportions of two or more
groups, the null hypothesis is that

H0: p1=p2=p3.....=p

where this p is the pooled proportion, the proportion in the summed groups =
n1+n2+n3+..../N1+N2+N3....

in the z-test between two proportions, p1 and p2 are put in the numerator
(p1-p2) while the pooled p is used in the denominator as part of Standard
error of the difference.  If you thisk in putting the numerator as p1-p(the
pooled p) there will be a problem of dependence as p(the pooled p) will
change as p1 changes.

Mostafa

>From: "syed gillani" <syed at saudionline.com.sa>
>To: <r-help at stat.math.ethz.ch>
>Subject: [R] Hypothesis test
>Date: Sat, 7 Apr 2001 06:11:42 +0300
>
>Hello,
>
>Is it reasonable to run a test of significance regarding a proportion in a
>group versus that in the whole population?
>What kind of problems can one face in analysis?
>
>Thanks.
>
>syed
>
>
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