Tag
anova
10 answered questions tagged “anova”. Browse and search all answers, or ask your own.
Searches the anova answers on this page. Search all answers
Do robust standard errors fix floor and ceiling effects?
Robust standard errors repair the uncertainty around a group difference, not the difference itself. What that means when scores pile up at a scale limit.
Read the answer →Is an F-test gate needed before Tukey's HSD?
Whether the overall F test must reject before follow-up tests between groups, what that gate does to false positives and power, and when F still helps.
Read the answer →How many participants do you need when comparing several treatment arms?
Plan a multi-arm study around the comparisons you will report, not the ANOVA F test, and see how a multiplicity correction changes the numbers.
Read the answer →Why does a t test use the t distribution and ANOVA the F distribution?
How the t, F and chi-square reference distributions are derived from the way each test statistic is built, and what to do when no formula exists.
Read the answer →Significant ANOVA but no significant pairwise comparisons: how can that happen?
Why a one-way ANOVA F test can reject while every pairwise or Tukey comparison does not (and the reverse), and how far apart their p values can get.
Read the answer →t tests vs the F test in regression: what is the difference?
Why regression output gives a t test for each coefficient and one overall F test, when the two agree exactly, and why they can point in opposite directions.
Read the answer →Confidence interval for eta squared: does the Fisher z shortcut work?
Why the Fisher z shortcut gives unreliable intervals for eta squared, and how to get an exact one from F and its degrees of freedom.
Read the answer →How to interpret the F statistic and p value in a one-way ANOVA
What the F ratio in an ANOVA table measures, how it maps onto the p value and the critical F, and what a significant F does and does not tell you.
Read the answer →Planned contrasts vs post hoc tests: why do they give different p-values?
Why one comparison gets different p-values as a planned contrast, a Tukey test or a Bonferroni test, and when to use each.
Read the answer →t test vs ANOVA with two groups: are the assumptions really different?
Why a pooled t test and a one-way ANOVA on two groups give the same p value, and why their normality assumptions are the same thing stated two ways.
Read the answer →