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University of Phoenix Material

Dr. Zak Case Study

Instructions

Read the following case study. Use the information in the case study to answer the accompanying follow-up questions. Although questions 1 & 2 have short answers, you should prepare a 150- to 200-word response for each of the remaining questions.

Case Study

Dr. Zak developed a test to measure depression. He sampled 100 university students to take his five item test. The group of students was comprised of 30 men and 70 women. In this group, four persons were African American, six persons were Hispanic, and one person was Asian. Zak’s Miraculous Test of Depression is printed below:

1. I feel depressed: Yes No

2. I have been sad for the last two weeks: Yes No

3. I have seen changes in my eating and sleeping: Yes No

4. I don’t feel that life is going to get better: Yes No

5. I feel happy most of the day: Yes No

Yes = 1; No = 0

The mean on this test is 3.5 with a standard deviation of .5.

Follow-Up Questions

1. Sally scores 1.5 on this test. How many standard deviations is Sally from the mean? (Show your calculations)

Because the Mean = 3.5 with a SD = .5 , and Sally’s score = 1.5, my calculations would be first 1.5 - 3.5 = -2, then -2 / .5 = -4. So in conclusion, this means that Sally is -4 standard deviations away from the mean.

(1.5 – 3.5) / (.5) = - 4

2. Billy scores 5. What is his standard score?

In order to determine the standard score here, we would have to calculate the z – score using the raw score of (5) minus the mean (3.5), devided by standard deviation (.5). So first we have the equation 5 - 3.5 = 1.5, followed by the equation of 1.5 /. 5 = 3. As a result of this, we can determine that Billy has a Standard score of 3.

(5 - 3.5) / (.5) = 3

3. What scale of measurement is Dr. Zak using? Do you think Dr. Zak’s choice of scaling is appropriate? Why or why not? What are your suggestions?

4. Do you think Dr. Zak has a good sample on which to norm his test? Why or why not? What are your suggestions?

5. What other items do you think need to be included in Dr. Zak’s domain sampling?

Depression is a serious illness, and if it is not examined to its fullest it can evolve into a serious case which can lead severe consequences. This study could benefit from asking more questions because asking more questions can provide further insight into how serious their depression is, and perhaps gauge what level of depression they are experiencing. Some other questions that can be asked can be, it is difficult for me to concentrate, I have trouble making decisions, my sleep patterns bad and having difficulty relaxing, I often feel nervous or anxious, committing suicide has come into my mind, you are no longer sexually driven, is depression present in your family history, you often feel sad or worthless.

The issue with this test is that people experience different forms of depression where some cases may not be as severe as others. There are many different factors that have an effect in the development of depression from changes in hormones, genetic predispositions, relationships, or the experience of internal and external stressors. The more questions that are involved in the testing, the more information that can be gathered to help produce effective results.

6. Suggest changes to this test to make it better. Justify your reason for each suggestion supporting each reason with psychometric principles from the text book or other materials used in your course.

7. Dr. Zak also gave his students the Beck Depression Inventory (BDI). The correlation between his test and the BDI was r =.14. Evaluate this correlation. What does this correlation tell you about the relationship between these two instruments?

References

Cohen, R. J., Swerdlik, M. E, & Sturman, E. D. (2013). Psychological testing and assessment: An introduction to tests and measurement (8th ed.). New York, NY: McGraw-Hill.