How do you interpret a 3 way ANOVA?
A three way interaction means that the interaction among the two factors (A * B) is different across the levels of the third factor (C). If the interaction of A * B differs a lot among the levels of C then it sounds reasonable that the two way interaction A * B should not appear as significant.
What are the three assumptions that need to be met to run an ANOVA?
The factorial ANOVA has a several assumptions that need to be fulfilled – (1) interval data of the dependent variable, (2) normality, (3) homoscedasticity, and (4) no multicollinearity.
How do you describe a 3 way interaction?
In short, a three-way interaction means that there is a two-way interaction that varies across levels of a third variable. One way of analyzing the three-way interaction is through the use of tests of simple main-effects, e.g., the effect of one variable (or set of variables) across the levels of another variable.
What does a significant 3 way interaction mean?
A statistically significant three-way interaction indicates that one or more of the three possible two-way interactions (a × b, a × c, and b × c) differ across the levels of a third variable. For example, the a × b interaction may differ for one level of c compared to another level of c.
How to interpret the three-way interaction in ANOVA?
2 Answers 2. A three way interaction means that the interaction among the two factors (A * B) is different across the levels of the third factor (C). If the interaction of A * B differs a lot among the levels of C then it sounds reasonable that the two way interaction A * B should not appear as significant.
Is there a two way interaction and a three way interaction?
To put it another way: A two way interaction A * B exists in reality (not statistically) along with a three order interaction A * B * C only if the way that the factors A and B interacts among the levels of the factor C is similar.
How to test for normality in a three way ANOVA?
Your data need only be approximately normal for running a three-way ANOVA because it is somewhat “robust” to violations of normality, meaning that this assumption can be a little violated and still provide valid results. You can test for normality using the Shapiro-Wilk test of normality, which is easily tested for using Stata.
Are there any outliers in Stata 3 way ANOVA?
The problem with outliers is that they can have a negative effect on the three-way ANOVA, reducing the accuracy of your results. Fortunately, when using Stata to run a three-way ANOVA on your data, you can easily detect possible outliers.