Question

A psychology professor is interested on how different study techniques affect students’ test performance. He required half of the class to study the material in 10 sessions of 1 hour each (i.e., distributed study) while the other half studied it in 1 session of 10 hours on the same day as the 10th session of the distributed-study group (i.e., crammed study). Five days after the last study session for both groups, he tested the students on the material. He expected the crammed-study group to obtain worse scores in the quiz than the distributed-study group.

1. H_o: m_distributed     m_crammed
2. H_a: m_distributed     m_crammed

Is this a one tailed test or a two tailed test? Why or Why not? and what would the symbols be?

Answer 1

It is to be tested if the crammed study group score is worse (less) than the distributed study group

Thus, it is to be tested

Hence, the null and alternative hypotheses are

Since it is to be tested if scores are worse (and not better and worse both), this is a one tailed test.

It is a right tailed test, since the alternative hypothesis contains the greater than sign

The symbol used is the greater than sign as it is to be tested if m_distributed is better than m_crammed

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