Introduction to Probability and Statistics for Engineers and Scientists

34 Chapter 2:Descriptive Statistics

FIGURE 2.12 Histogram of a bimodal data set.

TABLE 2.8 Temperature and Defect Data

Day Temperature Number of Defects

1 24.2 25

2 22.7 31

3 30.5 36

4 28.6 33

5 25.5 19

6 32.0 24

7 28.6 27

8 26.5 25

9 25.3 16

10 26.0 14

11 24.4 22

12 24.8 23

13 20.6 20

14 25.1 25

15 21.4 25

16 23.7 23

17 23.9 27

18 25.2 30

19 27.4 33

20 28.3 32

21 28.8 35

22 26.6 24

A useful way of portraying a data set of paired values is to plot the data on a two-
dimensional graph, with thex-axis representing thexvalue of the data and they-axis
representing theyvalue. Such a plot is called ascatter diagram. Figure 2.13 presents a
scatter diagram for the data of Table 2.8.