Section 2.3 More Graphs for Quantitative Data 65 Table 2.15 Particulate Emissions for 65 Vehicles, Rounded to Two Digits 1.5 0.9 1.1 1.3 3.5 1.1 1.1 0.9 1.3 0.9 0.6 1.3 2.5 1.5 1.1 1.1 2.2 0.9 1.8 1.5 1.2 1.6 2.1 6.6 4.0 2.5 1.4 1.4 1.8 1.1 1.6 3.7 0.6 2.7 2.6 3.0 1.2 1.0 1.6 3.1 2.4 2.1 2.7 1.2 3.3 3.8 1.3 2.1 6.6 1.2 3.1 0.5 0.3 0.5 3.4 3.5 2.7 1.9 5.9 4.2 3.5 3.6 3.1 3.3 4.6 We now follow the three-step process to obtain the stem-and-leaf plot. The result is shown in Figure 2.13. 0 3 5 5 6 6 9 9 9 9 1 0 1 1 1 1 1 1 2 2 2 2 3 3 3 3 4 4 5 5 5 6 6 6 8 8 9 2 1 1 1 2 4 5 5 6 7 7 7 3 0 1 1 1 3 3 4 5 5 5 6 7 8 4 0 2 6 5 9 6 6 6 Figure 2.13 Stem-and-leaf plot for the data in Table 2.15 Split stems Sometimes one or two stems contain most of the leaves. When this happens, we often use two or more lines for each stem. The plot is then called a split stem-and-leaf plot.We will use the data in Table 2.16 to illustrate the method. These data consist of scores on a final examination in a statistics class, arranged in order. Table 2.16 Scores on a Final Examination 58 66 68 70 70 71 71 72 73 73 75 76 78 78 79 80 80 80 81 82 82 82 82 83 84 86 86 86 87 88 89 89 89 90 92 93 95 97 Figure 2.14 presents a stem-and-leaf plot for these data, using the stems 5, 6, 7, 8, and 9. 5 8 6 6 8 7 0 0 1 1 2 3 3 5 6 8 8 9 8 0 0 0 1 2 2 2 2 3 4 6 6 6 7 8 9 9 9 9 0 2 3 5 7 Figure 2.14 Stem-and-leaf plot for the data in Table 2.16 Most of the leaves are on two stems, 7 and 8. For this reason, the stem-and-leaf plot does not reveal much detail about the data. To remedy this situation, we will assign each stem two lines on the plot instead of one. Leaves with values 0–4 will go on the first line, and leaves with values 5–9 will go on the second line. So, for example, we will do the following with the stem 7: 7 0 0 1 1 2 3 3 5 6 8 8 9 will become 7 0 0 1 1 2 3 3 7 5 6 8 8 9 The split stem-and-leaf plot is shown in Figure 2.15 on page 66. Note that every stem is given two lines, even those that have only a few leaves. Each stem in a split stem-and-leaf plot must receive the same number of lines.
navidi_monk_essential_statistics_1e_ch1_3
To see the actual publication please follow the link above