Question

A learning researcher is interested in the effectiveness of her new memory enhancement program. To test this program, she has 15 students learn a list of 50 words. Memory performance is measured using a recall test. After the first test, these same students are instructed as to how to use the memory improvement program and then learn a second list of 50 different words. Memory performance is again measured with the recall test. If you wanted to test the hypothesis to see if the memory program actually improves memory, 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 (nondirectional)? Why?

Answer 1

Since the same set of students are used before the memory improvement program and after the memory improvement program, we use a matched pairs t test.

The Hypothesis:

H0: = 0

Ha: > 0

Where is the mean of the differences of the population, and this is assumed to be normally distributed.

This is a one tailed (tight tailed) test because we want to test if the memory improvement program enhances the memory, that is if the number of words remembered increases.

The test statistic. t = / [Sd / Sqrt(n)], where = the sample mean of the differences and Sd is the standard deviation of the differences.

The p value and the critical values, will be calculated for degrees of freedom = n - 1, where n = number of participants.