Range
Topic: Geographical Data: Sources, Compilation and Processing · NCERT: Class 12, Ch 1 "Data - Its Source and Compilation"; Class 12, Ch 3 "Graphical Representation of Data"
Meaning
Range is the difference between the largest and the smallest value in a data set (maximum − minimum). It is the simplest measure of dispersion, which means how spread out values are. It is quick to find, but it uses only two values, so a single extreme figure can distort it. Geographers also use it to plan data: it decides how many classes to make and how wide each should be. For a choropleth map (a map that shades areas by value), the range is often divided by 5 to get five equal classes.
Example
On the Malwa plateau in Madhya Pradesh, normal rainfall runs from 825 mm in Mandsaur to 1,083 mm in Dewas. The range is 1,083 − 825 = 258 mm. Divided by 5, this gives choropleth classes about 51.6 mm wide.
Don't confuse with
- Class interval: it is the width of one class, such as 10 in the class 20–30. Range covers the whole data set, from the lowest value to the highest.
Related concepts
- Measures of dispersion
- Mean deviation
- Standard deviation
- Coefficient of variation
- Measures of relationship
- Correlation coefficient