1. 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?
Social science disciplines such as psychology employ measurements and statistics to determine individual behaviors and the frequency in which these behaviors occur. There are four scales of measurement that are used in psychological testing and they include nominal scale, ordinal scale, interval scale, and ratio scale. Dr. Zak designed a test to determine depression on a sample of one hundred university students. He used the ordinal scale of measurement in his Miraculous Test of Depression. According to Jackson (2008), an ordinal scale can be defined as a measurement scale in which items are ranked according to how more or less their characteristics are related.
The ordinal scale is characterized by its categories having a logical relationship to one another. This scale is appropriate for this particular study because each test-taker has a different amount of depression and there will be a fluctuation of depression levels. Most behavioral scientists usually use interval scales in their measurements because it allows them to calculate for the average, range, and standard deviation. The interval scale also allows for ranking of items, quantification, and comparison of magnitudes of differences between the items (Jackson, 2008). I suggest that interval scale of measurement is the most appropriate type of scaling as far as Dr. Zak's case study is concerned.
2. Do you think Dr. Zak has a good sample on which to norm his test? Why or why not? What are your suggestions?
The sample is not good for the test developed by Dr. Zak since it has increased heterogeneity and it is small in size. Heterogeneous sample is the sample that is comprised of components with varied characteristics for example sex, tribe, race, age, educational levels, and incomes. This sample is comprised of men and women as well as three races, that is, African American, Hispanic, and Asian. According to Gravetter & Wallnau, (2008), the Results from less heterogeneous samples are always reliable because the tendency for results biased is reduced and the accuracy is increased.
In observational studies, increasing heterogeneity reduces both sensitivity to bias and sampling variability hence accurate results. It is natural that most researchers prefer to use large samples so as the standard error will be smaller, there will be less uncertainty, and the inference will be better (Jackson, 2008). If the sample size is increased then the sampling variability is reduced. Therefore I suggest that Dr. Zak should decrease the sample homogeneity and increase the size so that most reliable results will be obtained.