Sage-Tips

Can chi-square be used for three 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.

How do you know if you should reject the null hypothesis chi-square?

If your chi-square calculated value is greater than the chi-square critical value, then you reject your null hypothesis. If your chi-square calculated value is less than the chi-square critical value, then you “fail to reject” your null hypothesis.

What does it mean if ANOVA is significant but post hoc is not?

Post hoc tests are an integral part of ANOVA. When you use ANOVA to test the equality of at least three group means, statistically significant results indicate that not all of the group means are equal. However, ANOVA results do not identify which particular differences between pairs of means are significant.

Does chi-square compare groups?

Chi-square can be thought of in several ways. The first way we can think of the chi-square test is as an analogy to the t-test in which we are interested in comparing two groups. Only chi-square is used instead, because the dependent variable is dichotomous.

How do you compare categorical variables between three groups?

If you are using categorical data you can use the Kruskal-Wallis test (the non-parametric equivalent of the one-way ANOVA) to determine group differences. If the test shows there are differences between the 3 groups. You can use the Mann-Whitney test to do pairwise comparisons as a post hoc or follow up analysis.

What is chi-square test explain its significance in statistical analysis?

A chi-square test is a statistical test used to compare observed results with expected results. The purpose of this test is to determine if a difference between observed data and expected data is due to chance, or if it is due to a relationship between the variables you are studying.

How do you accept the null hypothesis for a chi-square test?

Compare the computed chi-square statistic with the critical value of chi-square; reject the null hypothesis if the chi-square is equal to or larger than the critical value; accept the null hypothesis if the chi-square is less than the critical value.

Why square squaring the difference between the observed and the expected outcome does two things?

Why square? Squaring the difference between the observed and the expected outcome does two things: Any standardized difference that is squared will now be positive. Differences that already looked unusual – e.g. large standardized differences – will become much larger after being squared.

What if post hoc test is not significant?

If this test is not significant, there is no evidence in the data to reject the null and one then concludes that there is no evidence to suggest that the group means are different. Otherwise, post-hoc tests are performed to find sources of difference.

What should be done if the ANOVA results show that there is no significant difference?

If you had a more complex structure and the entire ANOVA showed non-significant differences, then you would make an omnibus conclusion that you did not detect any differences. You would use a post hoc (after the fact) test only if one or more sources of variance was significant.

What statistical test is used to test the difference between means of two groups?

t-test
A t-test is a type of inferential statistic used to determine if there is a significant difference between the means of two groups, which may be related in certain features.