Appendix A Questions for Discussion

  1. If you were to measure your friends’ love of classical music on a 5-point scale with 1 = no love at all and 5 = lots of love, how do you suppose the scores would be distributed? Would they be normally distributed, with most people answering at the midpoint, or would they be skewed? If skewed, would they be positively or negatively skewed? What would be the most appropriate measure of central tendency? How much variability would be in these scores— that is, would the standard deviation be high or low? [Apply]

  2. A brother and sister, fraternal twins, are arguing about who is taller, relatively speaking. The brother is 72 inches and the sister is 67 inches. In a 2004 report, the Centers for Disease Control (CDC) published data on the average heights of males and females (Ogden et al., 2004), indicating that 19-year-old males are, on average, 69.6 inches with a standard deviation of 4.97 and that 19-year-old women are, on average, 64.2 inches with a standard deviation of 4.56. Treat these data as if they come from the entire population of 19-year-olds and figure out who, in fact, is relatively taller. Hint: Calculate z-scores for both groups and ask yourself, “Who is farther away from the mean?” [Apply]

  3. What are some examples of variables that are positively correlated? Negatively correlated? How about variables that have zero correlation? [Comprehend]

  4. In the nineteenth episode of Season 20 of the popular Fox television program The Simpsons, Lisa laments that Springfield Elementary is fully 2 standard deviations below the mean on school performance. Explain to someone who has no exposure to the concept of z-scores what she means. Hint: Look at Figure A-7 for a refresher. [Apply]

  5. Imagine you learned of a study in which researchers randomly assigned individuals to memorize a list of words while either listening to music or not. Results indicated that there was a statistically significant difference in the number of items they were later able to recall, with those in the no music condition outperforming those in the music condition. What effect size (small, medium, or large) would be large enough for you to take these results to heart and perhaps change the conditions under which you study? What if the dependent variable had instead been grades? [Apply, Analyze]