## What is the meaning of multiple comparisons?

There is no strict definition of multiple comparisons in the statistics literature: it sometimes refers to comparing multiple groups between each other or versus a shared control group while in other cases it refers to comparing only two groups but based on multiple characteristics of theirs.

## What does compare treatment mean?

When there is some structure to the treatments, the best way to compare treatment means is to use orthogonal contrasts/planned F tests which subdivide the treatment SS to isolate the variation associated with a single degree of freedom. If there is no structure to the treatments, a multiple range test can be used.

**What is multiple comparisons in research?**

In statistics, the multiple comparisons, multiplicity or multiple testing problem occurs when one considers a set of statistical inferences simultaneously or infers a subset of parameters selected based on the observed values. The more inferences are made, the more likely erroneous inferences become.

### What is multiple comparisons in psychology?

In statistics, the multiple comparisons problem occurs when one subjects a number of independent observations to the same acceptance criterion that would be used when considering a single event.

### What is multiple comparison test example?

Multiple comparisons conducts an analysis of all possible pairwise means. For example, with three brands of cigarettes, A, B, and C, if the ANOVA test was significant, then multiple comparison methods would compare the three possible pairwise comparisons: Brand A to Brand B.

**What is the proper way to apply the multiple comparison test?**

The classic approach for solving a multiple comparison problem involves controlling FWER. A threshold value of α less than 0.05, which is conventionally used, can be set. If the H0 is true for all tests, the probability of obtaining a significant result from this new, lower critical value is 0.05.

#### Why do we need to compare treatment means and not treatment total?

It tells you how much more variability there is between treatment groups than within treatment groups. The larger that ratio, the more confident you feel in rejecting the null hypothesis, which was that all means are equal and there is no treatment effect.

#### Why do we use multiple comparison tests?

Multiple comparisons tests (MCTs) are performed several times on the mean of experimental conditions. When the null hypothesis is rejected in a validation, MCTs are performed when certain experimental conditions have a statistically significant mean difference or there is a specific aspect between the group means.

**When and why do we conduct multiple comparison procedures?**

## How many pairwise comparisons are possible?

“Pairwise” means that each comparison looks at the difference between the means of a pair of design conditions. “Multiple” reminds us that there will be at least three pairwise comparisons, in order to obtain a complete description of the pattern of mean differences among the IV conditions.