Contents
Can Chi-square compare 3 groups?
First, when you perform Chi-square test for the three groups together, you will get general idea about the differences between groups. Then you can perform the sub-effect test between only the group that had significantly higher prevalence with the other groups.
Can Chi-square test be used for proportions?
The chi-squared test works by calculating the frequencies we would expect to see in the cells if there were absolutely no association. It works like this. For the HIV test data, the proportion who accepted the test is 134/788.
Can you use Chi-square for more than two categories?
Chi-square can also be used with more than two categories. For instance, we might examine gender and political affiliation with 3 categories for political affiliation (Democrat, Republican, and Independent) or 4 categories (Democratic, Republican, Independent, and Green Party).
What is the difference between Chi-square and Z-test?
The Z-test is used when comparing the difference in population proportions between 2 groups. The Chi-square test is used when comparing the difference in population proportions between 2 or more groups or when comparing a group with a value.
What do you do after chi-square?
Following a Chi-Square test that includes an explanatory variable with 3 or more groups, we need to subset to each possible paired comparison. When interpreting these paired comparisons, rather than setting the α-level (p-value) at 0.05, we divide 0.05 by the number of paired comparisons that we will be making.
Is the Pearson chi square the same as the Z test?
As noted above, the Pearson chi-square statistic is equivalent to the Z test statistic which is also commonly used to test the equality of independent proportions. In fact, chi-square = Z 2. Consequently, the p-value for the two-sided Z test is the same as for the chi-square test.
How to do a chi square test when you only have proportions?
In SPSS you just indicate that one variable (the independent one) should come in the row, and the other variable (the dependent one) should come in the column of the cross table. Then you ask for row percentages and the Chi-square statistic.
Is the chi square statistic based on ranks?
The comparisons are based on ranks, and the test statistic is distributed as a chi-square. hope this helps. Yes, I was not precise. I was running K-W test (I just wrote about chi-square because it is based on such distribution).
Can a chi square test have more than one degree of freedom?
The chi-square test will now have more than one degree of freedom and a small p -value tells you that at least two of the proportions differ. See this note for how to do multiple comparisons to see which proportions differ.