Class interval
Topic: Geographical Data: Sources, Compilation and Processing · NCERT: Class 12, Ch 1 "Data - Its Source and Compilation"; Class 12, Ch 4 "Spatial Information Technology"
Meaning
A class interval is the size of a class in a frequency distribution. It equals the upper limit minus the lower limit. For example, the class 20–30 has a class interval of 10. The size of the class interval and the number of classes depend on the range of the data, which is the gap between the highest and lowest values. Equal class intervals make classes easy to compare.
Example
The geography marks of 60 students range from 02 to 96. They can be grouped into ten classes with a class interval of 10 each: 0–10, 10–20 and so on up to 90–100. In the inclusive method (20–29, 30–39), each class still covers ten values.
Don't confuse with
- Class limits: these are the two end values of a class (for example 20 and 30). The class interval is the gap between them.
Related concepts
- Grouping of data
- Tally marks
- Frequency distribution
- Cumulative frequency
- Exclusive method
- Inclusive method
- Frequency polygon
- Ogive