Me and Psychology

Additional Practice Exercises

(Hypothesis testing, parametric and non-parametric tests and related issues)

Question 1

A psychologist from the Health and Well-being Centre at the UFS wants to determine the effectiveness of a psychotherapy program to reduce 1st year students’ stress levels during exams. She decided to ask all the students who reported to the centre for help on how to deal with high stress levels during March of 2013 (N=40), to participate in the research. She randomly assigned 20 students to the control group (X₁) and 20 students to the experimental group (X₂). She contracted with the control group that she will also give them an opportunity to participate in the program (April 2012) after the completion of the study. After the experimental group completed the psychotherapy program she measures all the students stress levels with the Stress Response Scale (SRS). She then uses the appropriate test statistic to determine if the program was effective. She calculated a tc-value = 1.3 and sets = 0.01.

a. State the null and research hypotheses for this research project.

b. Is this a one-tailed or two-tailed test? Motivate your answer.

c. What level of significance has the researcher chosen?

d. Why is the t-test for independent groups the most appropriate test statistic in this case?

e. Determine the degrees of freedom.

f. Determine the critical value for rejection.

g. Will you retain or reject the null hypothesis? Motivate your answer.

h. Interpret your result and write it in statistical terms.

i. What is the probability that the researcher made a type 1-error?

j. What is the difference between a type 1 and a type 2 error?

k. Identify the research type.

l. identify the research design.

m. What type and method of sampling did the researcher apply?

n. What ethical issue might be relevant to this research study and how did the researcher try to solve this problem?

Question 2

A psychologist from the Wellness department of a big...