Howell 9e_TBChapter 3

Chapter 3—Displaying Data MULTIPLE CHOICE QUESTIONS 3.1 Frequency distributions are used a) as a first step in examining data. b) as a screening device to identify questionable values. c) to organize data. d) *all of the above 3.2 + Assume that you have a set of data with 70 values spread fairly evenly between 0 and 100. The optimal number of categories for a histogram of these data would be approximately a) 4 b) *10 c) 25 d) 50 3.3 The “real lower limit” of an interval in a histogram is a) the lowest integer value for scores in that interval. b) the midpoint of the interval. c) *the lowest continuous value that would be rounded up into that interval. d) the smallest width of the interval. 3.4 + Outliers are a) *extreme or unusual values. b) the lowest value in a data set. c) the lowest and highest scores in a data set. d) all of the above 3.5 + If you created a stem-and-leaf display of the math SAT scores of all entering students in a large Midwestern state university, the stem would best be a) the numbers 0 through 10. b) the numbers 200 through 800. c) *the numbers 2 through 8. d) it is impossible to tell 3.6 If you created a stem-and-leaf display of the math SAT scores of all entering students in a large Midwestern state university, the leaves would most likely be a) the numbers 2 through 8. b) *the numbers 0 through 9 (with code |6|5 = 650). c) t, f, c. d) the symbols * and .

Test Bank 3.7 In the text there was a stem-and-leaf display showing the performance of students who attended class regularly and those who often skipped class. This display illustrated a) that poor attendees did more poorly than good attendees. b) the shape of the two distributions. c) the dispersion of the two distributions. d) *all of the above 3.8 + Assume that we had the following set of data: Score 11 12 17 18 19 20 21 22 23 24 25 Frequency 2 1 5 8 6 12 13 10 15 9 8 These data would most likely be characterized as a) positively skewed. b) normal. c) *negatively skewed. d) uniformly distributed. 3.9 + For the data referred to in the previous question, the distribution would best be called a) bimodal. b) *unimodal. c) symmetric. d) balanced. 3.10 When we plot a histogram, the values on the X axis are a) the real lower limits and real upper limits b) the midpoints c) the integers closest to the boundaries. d) *any of the above, depending on what makes the most sense at the time 3.11 A stem-and-leaf display is often a) a simplified representation of the underlying data. b) a quick way to draw a histogram. c) more informative than the corresponding histogram. d) *all of the above 215

Chapter 3 3.12 The following graphic is adapted from one in Wainer (1984), plotting the number of private and public elementary schools (in thousands) in the U.S. between 1930 and 1970. Wainer was presenting it as a bad example, and I have made it worse. What is bad about this example? 1930 1940 1950 1960 1970 0.00 50.00 100.00 150.00 200.00 250.00 300.00 Thousands of Schools Private Public a) The three dimensional effect only makes the graph harder to read. b) Any change in the number of private schools is difficult to see. c) The time intervals on the abscissa are too broad. d) *a and b but not c 3.13 + The Center for Disease Control has published statistics relating maternal smoking to low birth weight. The data follow in terms of the percentage of birth weights < 2500 grams for mothers in each of the two groups. 1989 1990 1991 1992 1993 Smokers 11.36% 11.25 11.41 11.49 11.84 NonSmokers 6.02% 6.14 6.36 6.35 6.56 Which of the following ways of presenting the data would be most informative? a) a histogram b) *a time series graph with a line for smokers and one for non-smokers c) two pie charts d) a stem-and-leaf display 3.14 The data in the previous question show a much higher incidence of low birth weight babies from mothers who smoke. This finding is likely to be a reliable one because a) everyone knows that smoking is a bad thing. b) the smokers rate of low birth weight is twice that of the non-smokers. c) *the pattern of differences occurs reliably over each of 5 years. d) there is a general increase in low birth weight over the years. 3.15 Inglehart (1990) presented data on the mean Satisfaction with Life scores for 24 developed countries. These data follow: Country Mean Satisfaction Country Mean Satisfaction Portugal 5.5 Canada 7.2 Greece 5.8 Belgium 7.3 Japan 6.4 Britain 7.5 216