Can a t test be used as a post hoc test Why or why not?
When the ANOVA is significant, post hoc tests are used to see differences between specific groups. post hoc tests control the family-wise error rate (inflated type I error rate) due to multiple comparisons. t-test does not control the inflated type I error rate.
Which is the difference between post hoc test and t-test?
When I look at the posthoc Tukey test there is no significance revealed to a particular group (despite ANOVA p<0.05), however comparison of one treated group to the control via unpaired t-test does show significant difference of p<0.05 to particular group. Which is the reliable answer? Which post hoc test is best?
What’s the difference between ” post hoc ” and ” planned comparisons “?
Difference between “planned comparisons”, “post-hoc tests”, “multiple comparison tests” , “post tests”, and “orthogonal comparisons”. The ANOVA calculations test the null hypothesis that all groups of data really are sampled from distributions that have the same mean (so any observed differences are just due to coincidences of random sampling).
Why is ANOVA significant but post-hoc test not?
However, to perform any type of anova (single factor, two-way, three-way etc) same assumptions should be considered (normality, symmetry,homogeneity of variances, interval data of the dependent variable, absence of multicollinearity, outliers etc.) so you should perform Hartley-test, Chi square etc and check skewness and kurtosis of distribution.
When is the independent sample t test not trustworthy?
There is no relationship between the subjects in each sample. This means that: When this assumption is violated and the sample sizes for each group differ, the p value is not trustworthy. However, the Independent Samples t Test output also includes an approximate t statistic that is not based on assuming equal population variances.