Class interval

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One of the non-overlapping intervals into which the range of values of measurement data, and occasionally whole-number data, is divided. Each value in the distribution must be able to be classified into exactly one of these intervals.
 
Example 1 (Measurement data)

The number of hours of sunshine per week in Grey Lynn, Auckland, from Monday 2 January 2006 to Sunday 31 December 2006 is recorded in the frequency table below. The class intervals used to group the values of weekly hours of sunshine are listed in the first column of the table.

Hours of sunshine Number of weeks
5 to less than 10
10 to less than 15
15 to less than 20
20 to less than 25
25 to less than 30
30 to less than 35
35 to less than 40
40 to less than 45
45 to less than 50
2
2
5
9
12
10
5
6
1
Total 52

Example 2 (Whole-number data)

Students enrolled in an introductory Statistics course at the University of Auckland were asked to complete an online questionnaire. One of the questions asked them to enter the number of countries they had visited, other than New Zealand. The class intervals used to group the values are listed in the first column of the table.

Number of countries visited Frequency
0 – 4
5 – 9
10 – 14
15 – 19
20 – 24
25 – 29
30 – 34
446
172
69
19
14
4
3
Total 727

Alternatives: bin, class

Curriculum achievement objectives references
Statistical investigation: Levels (4), (5), (6), (7), (8)