Using the guidelines given in this chapter (and Table 1.4), name an appropriate statistical analysis for each of the following imaginary studies. Also, state which variable is the predictor or independent variable and which variable is the outcome or dependent variable in each situation. Unless otherwise stated, assume that any categorical independent variable is between-S (rather than within-S), and assume that the conditions required for the use of parametric statistics are satisfied.
Case I: A researcher measures core body temperature for participants who are either male or female (i.e., Gender is a variable in this study). What statistics could the researcher use to see if mean body temperature differs between women and men?
Case II: A researcher who is doing a study in the year 2000 obtains yearbook photographs of women who graduated from college in 1970. For each woman, there are two variables. A rating is made of the “happiness” of her facial expression in the yearbook photograph. Each woman is contacted and asked to fill out a questionnaire that yields a score (ranging from 5 to 35) that measure her “life satisfaction” in the year 2000. The researcher wants to know whether “life satisfaction” in 2000 can be predicted from the “happiness” in the college yearbook photo back in 1970. Both variables are quantitative, and the researcher expects them to be linearly related, such that higher levels of happiness in the 1970 photograph will be associated with higher scores on life satisfaction in 2000. (Research on these variables has actually been done; see Harker & Keltner, 2001.)
Case III: A researcher wants to know whether preferred type of tobacco use (coded 1 = no tobacco use, 2 = cigarettes, 3 = pipe, 4 = chewing tobacco) is related to Gender (coded 1 = male, 2 = female).
Case IV: A researcher wants to know which of five drug treatments (Group 1 = Placebo, Group 2 = Prozac, Group 3 = Zoloft, Group 4 = Effexor, Group 5 = Celexa) is associated with the lowest mean score on a quantitative measure of depression (the Hamilton Depression Rating Scale).