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)

a. What statistical test would be appropriate in this case? Explain the rationale for your answer.

b. State the null and alternative hypotheses in words.

c. State the null and alternative hypotheses in statistical symbols

d. Would the test be right-tailed, left-tailed or two-tailed? Explain the rationale for your answer.

e. Describe a potentially confounding variable and explain how that might affect the conclusions from the study.

Answer 1

(a)

2 Dependent Samples t test (paired t test)

Explanation: The 2 samples are not independent. They are correlated pairs. The same sample is measured twice: before the treatment and after the treatmet

(b)

H0:Null Hypothesis:   The learning ability score after the treatment is not more than the score before the treatment

HA: Alternative Hypothesis:   The learning ability score after the treatment is more than the score before the treatment

(c)

H0: Null Hypothesis: 0

HA: Alternative Hypothesis: < 0

where = Score Before training - After training

(d)

Left tailed

(e)

Potentially confounding variable is the inherent ability of an individual in learning from an training program is not the same for all people. Some persons learn fast whereas some other are dull. So, the results of the experimentation may not reflect adequately in their learning scores.