# st: Chi-square test for Categorical Data Analysis

 From "Hugh Colaco" To statalist Subject st: Chi-square test for Categorical Data Analysis Date Tue, 18 Sep 2007 16:40:25 -0400

```Dear Statalisters,

I am working on some data from a survey and have a question about the
chi-square test. I have 2 cohorts - lets call them A and B. Assume
N=100 for A and N=50 for B.

from below. Assume the income ranges are:-

\$0 - \$25,000
\$25,001 - \$50,000
\$50,001 - \$100,000
\$100,001 - \$150,000
\$150,001 - \$200,000
\$200,001 - \$500,000
\$500,001 or more

Rather than report so many income ranges, I would now like to report
just two, based on the median of all 150 participants. So, I will have
4 groups in all (i.e. Group A below median income, Group A equal to or
above the median income, Group B below median income, Group B equal to
or above the median income).

I would like to then run a chi-square test to see if there is a
difference in the distributions. Is this valid?

Second question - does the chi-square test convey any additional
information other than the fact that the distributions are different?
That is, since only the number of observations in each group is being
tested, can I, for example, conclude that Group A is making
significantly more income than Group B?

Finally, can somebody give me a good reference for the chi-square test
for categorical data analysis?

--
Hugh
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```