Question

A team of psychologists have developed an experimental treatment program for a learning disorder with the expectation that the treatment would enable recipients to score higher than before on a test of learning ability. To test the treatment, they randomly select a pool of 30 volunteers who have been diagnosed with the disorder and who have volunteered for the treatment program. Following treatment, the participants are retested on the learning ability test and their scores compared to earlier scores. Complete the following. (1 point each)

1. What statistical test would be appropriate in this case? Explain the rationale for your answer.
2. State the null and alternative hypotheses in words.
3. State the null and alternative hypotheses in statistical symbols
4. Would the test be right-tailed, left-tailed or two-tailed? Explain the rationale for your answer.
5. Describe a potentially confounding variable and explain how that might affect the conclusions from the study.

Answer 1

(a) Dependent t test (also called paired samples t - test).

EXPLANATION The same 30 volunteers are measured before ad after treatment program. So, the two samplesare not independent. Thy are correlated pairs.

(b) Null Hypothesis: Score before treatment is greater than or equal to Score after treatment

Alternative Hypothesis: Score after treatment is greater than or equal to Score beforer treatment

(c) H0: Null Hypothesis:

HA: Alternative Hypothesis:

(d) The test is Left Tailed.

EXPLANATION: The Alternative Hypothesis has "<" sign.

(e) Potentially confounding variable is that all the 30 volunteers participating in the study will not be of the same learning disorder. So, the result of the study will be meaningful only when all the participants are equal.