74 Chapter 2 Graphical Summaries of Data 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 Average Salary (million $) 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 a. What is the first year that the average salary was more than one million dollars? b. In 1994, the players went on strike, and the last two months of the season were canceled. In 2003, a new labor agreement was reached that penalized teams that paid unusually high salaries. How did these events affect the average salary? Extending the Concepts 33. Elections: In U.S. presidential elections, each of the 50 states casts a number of electoral votes equal to its number of senators (2) plus its number of members of the House of Representatives. In addition, the District of Columbia casts three electoral votes. Following are the numbers of electoral votes cast for president for each of the 50 states and the District of Columbia in the election of 2008. 9 3 10 6 55 9 7 3 3 27 15 4 4 21 11 7 6 8 9 4 10 7 12 17 10 6 11 3 5 5 4 15 5 31 15 3 7 7 21 4 8 3 11 34 5 3 13 11 5 10 3 a. Construct a split stem-and-leaf plot for these data, using two lines for each stem. b. Construct a frequency histogram, with the classes chosen so that there are two classes for each stem. c. Explain why the stem-and-leaf plot and the histogram have the same shape. Answers to Check Your Understanding Exercises for Section 2.3 1. a. 12 13 14 15 16 17 18 19 b. 12 4494 13 63 14 9583 15 70156857 16 330601 17 12 18 2 19 552 c. 12 4449 13 36 14 3589 15 01556778 16 001336 17 12 18 2 19 255 2. a. 1997–1999 b. False c. Increasing 1991–1997; decreasing 1999–2007 d. False SECTION 2.4 Graphs Can Be Misleading Objectives 1. Understand how improper positioning of the vertical scale can be misleading 2. Understand the area principle for constructing statistical graphs 3. Understand how three-dimensional graphs can be misleading Statistical graphs, when properly used, are powerful forms of communication. Unfortunately, when graphs are improperly used, they can misrepresent the data and lead people to draw incorrect conclusions.We discuss here three of the most common forms of misrepresentation: incorrect position of the vertical scale, incorrect sizing of graphical images, and misleading perspective for three-dimensional graphs. Objective 1 Understand how improper positioning of the vertical scale can be misleading Positioning the Vertical Scale Table 2.20 is a distribution of the number of passengers, in millions, at Denver International Airport in each year from 2002 to 2008.
navidi_monk_essential_statistics_1e_ch1_3
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