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

Test Bank Spain 6.5 U.S.A. 7.55 Italy 6.5 Ireland 7.7 South Africa 6.6 Luxemburg 7.75 France 6.6 Finland 7.75 Argentina 6.72 Norway 7.85 Hungary 6.95 Australia 7.9 Austria 7.1 Switzerland 7.95 Netherlands 7.2 Denmark 8.0 West Germany 7.2 Sweden 8.0 A histogram of these data would be a) *reasonably symmetric. b) positively skewed. c) very bimodal. d) impossible to draw. 3.16 On October 25, 1978 the Washington Post presented a graphic showing the declining purchasing power of the U.S. dollar. What was worth $1 in 1958 was worth only $0.44 in 1978. They illustrated the decline in value by showing a dollar that was 3 inches by 1 inch in 1959, and one that was 1.32 inches (44% of 3 inches) by .44 inches in 1978. What is wrong with this kind of a display? a) You can’t equate dollars in 1958 with dollars in 1978. b) The dollar actually increased in purchasing power over that period of time. c) There is nothing wrong with doing this. d) *The area of the dollar is reduced by more than .44%. 3.17 + “5s” represents what numbers on a stem-and-leaf display according to Tukey? a) 50-51 b) 52-53 c) 54-55 d) *56-57 3.18 + On a recent fundraising drive, most of the 30 volunteers raised between $10 and $50 each. However, Brian and Karen each raised over $100. Which of the following is true? a) *The amounts of money raised by Brian and Karen are outliers. b) The data would best be represented three-dimensionally. c) The data appear negatively skewed. d) The data should be represented on a back-to-back stem-and-leaf display. 3.19 + Which of the following is the least important characteristic of graphics? a) clarity b) *beauty c) simplicity d) neatness 217

Chapter 3 3.20 Someone asks you if you have seen the movie Titanic . Before you answer, you look back into your memory for all of the movies you have ever seen and review the titles one at a time. This is an example of a) parallel processing b) frequent processing c) *sequential processing d) sensory memory 3.21 + A data set of test scores consisted of the following: 36 42 55 60 63 75 77 78 79 80 83 83 84 84 85 85 86 87 91 91 92 94 99 On a stem-and-leaf display, the values of the tens digits (3 – 9) are a) the trailing digits. b) the leaves. c) the less significant digits. d) *the stems. 3.22 The above data set appears a) positively skewed. b) *negatively skewed. c) normally distributed. d) bimodal. 3.23 In the above data set, the outliers would most likely be a) 94 and 99. b) 36 and 99. c) *36 and 42. d) There are no outliers. 3.24 A normal distribution must a) have outliers. b) *be symmetric. c) be positively skewed. d) be negatively skewed. 3.25 In making plots of data, which of the following rules is true? a) Three-dimensional plots should never be used. b) Rules of graphical presentation are prescriptive and should never be broken. c) The ultimate goal in making plots is to make data attractive. d) *The point of representing data graphically is better communication. 218

Chapter 3 3.33 + If the distribution of the ages of people were positively skewed, which of the following is most likely correct? a) There are about the same number of young people as old people. b) *There are more young people than old people. c) There are more old people than young people. d) none of the above 3.34 A negatively skewed distribution a) *has a tail pointing to the left. b) has a tail pointing to the right. c) is symmetric. d) is also positively skewed. 3.35 Displaying data on graphs a) can aid communication of results to an audience. b) can organize data in logical order. c) can be done with computers. d) *all of the above 3.36 Boxplots are graphical displays that a) emphasize the basic characteristics of the data. b) focus on the median and spread of the data. c) allow us to visually see how two or more distributions compare. d) *all of the above 3.37 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) 50 c) *10 d) 25 TRUE/FALSE QUESTIONS 3.38 [TRUE] Given the following numbers, 10, 25, 37, and 40, the leading digits are 1, 2, 3, and 4. 3.39 [FALSE] The leading digits are the leaves in a stem and leaf plot. 3.40 [FALSE] The following is a frequency distribution. 0 12223 1 00023334489 3 0111222344456667789 4 0000111122355799 5 00000002335 220

Test Bank 3.41 [FALSE] In a frequency distribution, the number of observations that fall within an interval is plotted. 3.42 [FALSE] When a variable has many values, and each value occurs rarely, a stem- and-leaf plot is preferable to a histogram. 3.43 [TRUE] 87 is the midpoint of the interval from 85 to 89. 3.44 [TRUE] Skewness refers to how symmetrical or assymetrical a distribution is. 3.45 [FALSE] An outlier refers to data that falls toward the middle of a distribution. 3.46 [TRUE] The following graph is unimodal. 0 5 10 15 20 25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Value F req u en c 3.47 [TRUE] The previous graph is symmetrical. OPEN-ENDED QUESTIONS The next six questions are based on the following data. 1 9 15 20 25 29 32 40 47 2 10 16 21 26 30 35 42 49 3 11 16 22 27 31 35 42 50 5 13 18 24 28 31 35 43 50 6 14 19 24 28 32 37 45 51 7 14 20 25 29 32 39 46 59 3.48 Create a stem and leaf plot for these data. 3.49 Create a frequency distribution for these data. 3.50 Create a histogram for these data using an interval of 5 (e.g., 0 to 5, 6 to 10). 3.51 Is the distribution symmetrical? 221

Test Bank 3.56 Answer the following questions based on the graph below. a) Is the graph symmetrical? b) Is the graph unimodal or bimodal? c) Do the data appear skewed? If so, positively or negatively? d) Do there appear to be outliers? If so, for what values? 3.57 Use two terms to describe the following data. Score 18.2 17.2 16.2 15.1 14.1 13.1 12.1 11.0 10.0 9.0 7.9 6.9 5.9 4.9 3.8 2.8 1.8 Frequency 12 10 8 6 4 2 0 223