Mode

TL;DR

• The mode identifies the most frequent value in a data set.
• It is robust to extreme values or outliers and can better reflect the common observation when mean or median are misleading.
• A data set may have one mode, two modes (bimodal), or multiple modes (multimodal).

Definition

The mode is a statistical measure that represents the most frequent value in a data set.

Explanation

Mode summarizes a set of observations by indicating which value occurs most often. Because it depends only on frequency, the mode is not affected by extreme values or outliers, making it useful for skewed distributions or small samples. When a data set contains multiple values with the same highest frequency, it is described as bimodal (two modes) or multimodal (more than two modes).

Examples

Exam scores

Consider a data set of exam scores for a class of students. The mode is the most frequent score. For example, if the majority of students scored 85 on the exam, the mode would be 85.

Survey responses

In survey data asking respondents for their preferred method of transportation to work, the mode is the most commonly chosen method (for example, driving or public transportation).

Salaries

For a company’s salary data, if a few highly paid executives raise the mean substantially, the mode can better represent the most common salary among employees.

Use cases

• Summarizing a set of observations to show the most common value.
• Situations where mean or median may not accurately represent the typical observation, such as when extreme values or skewed distributions are present.
• Small samples where frequency of specific values is the primary interest.

Notes or pitfalls

• The mode is not affected by extreme values or outliers.
• A data set can have more than one mode; such distributions are called bimodal or multimodal.

Related terms

• Mean
• Median
• Bimodal
• Multimodal
• Outliers