Bimodal and multimodal distribution

Indian Economy glossary

Also called: Bimodal distribution, Multimodal distribution · Topic: Economic Data: Census, NSS, Surveys and Statistical Tools · NCERT: Class 11, Ch 5 "Measures of Central Tendency"; Class 11, Ch 8 "Use of Statistical Tools"

Meaning

The mode is the value that occurs most often. A distribution can be classified by how many modes it has:

  • Unimodal: one mode.
  • Bimodal: two modes.
  • Multimodal: more than two modes.
  • No mode: every value occurs equally often.

Two or more peaks often mean the data mix two different groups. For example, one data set might mix a poorer group and a richer group. A single average can hide this.

Example

  • In the series 2, 3, 3, 5, 7, 7, both 3 and 7 occur twice, so the series is bimodal.
  • In the series 1, 1, 2, 2, 3, 3, 4, 4, every value occurs twice, so there is no mode.

Don't confuse with

  • Symmetric distribution: here the mean, median and mode coincide at one central peak. A bimodal distribution has two separate peaks.

Related concepts

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