Contents
What test do you use to compare more than two means?
-way analysis of variance (ANOVA)
For a comparison of more than two group means the one-way analysis of variance (ANOVA) is the appropriate method instead of the t test. As the ANOVA is based on the same assumption with the t test, the interest of ANOVA is on the locations of the distributions represented by means too.
What is comparison wise error?
in a test involving multiple comparisons, the probability of making at least one Type I error over an entire research study. The experiment-wise error rate differs from the testwise error rate, which is the probability of making a Type I error when performing a specific test or comparison.
Why is family wise error rate important?
FWER control limits the probability of at least one false discovery, whereas FDR control limits (in a loose sense) the expected proportion of false discoveries. Thus, FDR procedures have greater power at the cost of increased rates of type I errors, i.e., rejecting null hypotheses that are actually true.
How is the familywise error rate calculated in ScienceDirect?
Suppose there are ten groups with 50 observations per group. Let nine of the means be identical, with one very different from the rest. Thus, the overall F -test, using 9 and 40 degrees of freedom, (almost) always rejects its null hypothesis when used at level α = 0.05.
When to use a repeated measures ANOVA in statistics?
A repeated measures ANOVA will not inform you where the differences between groups lie as it is an omnibus statistical test. The same would be true if you were investigating different conditions or treatments rather than time points, as used in this example.
When is the experiment wise error rate called conservative?
If the experiment-wise error rate < .05 then the error rate is called conservative. If it is > .05 then the error rate is called liberal. There are two types of follow up tests following ANOVA: planned (aka a priori) and unplanned (aka post hoc or posteriori) tests.
How to calculate the type I error rate?
With 3 separate tests, in order to achieve a combined type I error rate (called an experiment-wise error rate or family-wise error rate) of .05 you would need to set each alpha to a value such that 1 – (1 – α) 3 = .05, i.e. α = 1 – (1 – .05) 1/3 = 0.016952.