Notice that in Figure 2.8 I did not list the extreme values as I did in the others. I used
the word High in place of the stem and then inserted the actual values. I did this to high-
light the presence of extreme values, as well as to conserve space.
Stem-and-leaf displays can be particularly useful for comparing two different distribu-
tions. Such a comparison is accomplished by plotting the two distributions on opposite
sides of the stem. Figure 2.9 shows the actual distribution of numerical grades of males and
females in a course I taught on experimental methods that included a substantial statistics
component. These are actual data. Notice the use of stems such as 6* (for 60–64), and 6.
(for 65–69). In addition, notice the code at the bottom of the table that indicates how en-
tries translate to raw scores. This particular code says that |4*|1 represents 41, not 4.1 or- Finally, notice that the figure nicely illustrates the difference in performance between
the male students and the female students.
26 Chapter 2 Describing and Exploring Data
Figure 2.8 Stem-and-leaf display for reaction time dataRaw Data Stem Leaf
36 37 38 38 39 39 39 40
40 40 40 41 41 41 42 42
42 43 43 43 43 43 44 44
44 44 44 45 45 45 45 45
45 46 46 46 46 46 46 46
46 46 46 46 47 47 47 47
47 47 47 47 47 48 48 48
48 49 49 49 49 49 50 50
50 50 50 51 51 51 51 51
51 51 51 51 51 51 51 52
52 52 52 52 52 52 52 52
52 53 53 53 53 53 53 53
53 54 54 54 54 54 54 55
55 55 55 55 55 55
...High3s
3.
4*
4t
4f
4s
4.
5*
5t
5f
5s
5.
6*
6t
6f
6s
6.
7*
7t
7f
7s
7.
8*
8t
8f
8s
8.
9*
9t
9f
9s
9367
88999
0000111
22233333
44444555555
66666666666777777777
888899999
00000111111111111
222222222233333333
4444445555555
66666666667777777
88888888888899999999999
00000000000011111111111
222222222222223333333333
444444455555555
6666666677777777777777
889999999
01111
22222222333
44444455
666677
88899
00011
2333
5
67
8
044558
104; 10; 125