Question

An experiment is done to compare the effects of three situations: Situation 1 is tested in a “no-stress,” baseline situation; Situation 2 does a mental arithmetic task; and Situation 3 participants do a mock job interview. At the end of each session, the participants self-report their anxiety on a scale that ranges from 0=no anxiety to 20=extremely high anxiety. The researcher wants to know whether, overall, anxiety levels differed across these three different situations. Each of the 21 participants was randomly assigned to one of the three stress conditions. If you wanted to test the hypothesis to see if there was any effect of the three situations on the subjects' ratings of anxiety, what would be the appropriate analysis? What would be the null and alternative hypotheses for this test? Would the alternative hypothesis be one-tailed (directional) or two-tailed (non-directional)? Why? Explain!

Answer 1

Here there are three samples which is more than 2, and we perform test on means in this problem. hence we One-Way Analysis of Variance.

Hypothesis:

H0: All the group means are equal. ()

H1: Atleast one group mean is significantly different from the other.

The alternative hypothesis is non-directional hypothesis, because here we cannot test which group mean is more or less than the other, we only perform whether any one group mean is significantly different from the rest groups which means the mean can be greater or less than the other group means. hence it is non directional.