# What is the difference between omnidirectional and non-directional?

This part covers non-directional (two-tailed) techniques which are appropriate when the experimenter predicts an effect, but doesn't predict the direction of the effect.

## By contrast, in general, the F test is used in non-directional tests.

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### Here is what we do for directional hypothesis testing:

This error has less grevious implications, so we are will to err in this direction (of not concluding the experiment had an effect when it, in fact, did).

### Nondirectional Hypotheses - SAGE Research Methods

Note that when effective leader essay the number of samples is k=2, the analysis of variance (standard weighted- means analysis) is equivalent to a non-directional t-test with F=t 2 Start studying Research Methods and Statistics.

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## Directional or Non-directional Hypothesis for …

When I took a methods course, I was told to avoid making a directional hypothesis. I understand the reason. Now however, I often see hypotheses like these: "We hypothesized that reaction time will decrease due to the treatment". It's rare to read research papers that have non-directional hypotheses (at least in my limited readings). If the researcher makes a directional hypothesis, I would assume that he will need to run a one-tailed test. From what I remember, if the results go the opposite direction--i.e., reaction time increases--our researcher failed to reject the null.