18 Chapter 2 Describing and Exploring Data
Table 2.2 Frequency distribution of reaction times
Reaction Time, in Reaction Time, in
100ths of a Second Frequency 100ths of a Second Frequency
36 1 71 4
37 1 72 8
38 2 73 3
39 3 74 6
40 4 75 2
41 3 76 4
42 3 77 2
43 5 78 3
44 5 79 2
45 6 80 3
46 11 81 2
47 9 82 1
48 4 83 3
49 5 84 0
50 5 85 1
51 12 86 1
52 10 87 1
53 8 88 1
54 6 89 0
55 7 90 1
56 10 91 0
57 7 92 0
58 12 93 0
59 11 94 2
60 12 95 2
61 11 96 0
62 14 97 0
63 10 98 1
64 7 99 0
65 8......
66 8......
67 14 104 2
68 2......
69 7 125 1
70 12.2 Histograms
From the distribution given in Table 2.1 we could easily graph the data as shown in Figure 2.1.
But when we are dealing with a variable, such as this one, that has many different values,
each individual value often occurs with low frequency, and there is often substantial fluctua-
tion of the frequencies in adjacent intervals. Notice, for example, that there are fourteen 67s,
but only two 68s. In situations such as this, it makes more sense to group adjacent values