Chi-Square Tests
We use chi-square tests to analyze differences between population proportions
based on two or more samples and the independence of two categorical
variables.
Chi-square test for the difference between two population
proportions
If we are interested in comparing the counts of categorical responses between
two independent groups, we can develop a two-way contingency table.
Sample/Response type
Sample 1
Sample 2
Total
Yes
1
X
2
X
X
No
11
nX−
22
nX−
nX−
Total
1
n
2
n
n
Since the above table has 2 columns and two rows, it is a 2 x 2 contingency
table.
Example. The number of guests who said that they will choose the same hotel
again
Sample/Response type
Total
