Definition:Frequency (Descriptive Statistics)

Definition

Let $S$ be a sample or a population.

Let $\omega$ be a qualitative variable, or a class interval of a quantitative variable.

The frequency of $\omega$ is the number of individuals in $S$ satisfying $\omega$.

Examples

Arbitrary Example

Consider the sample:

$2, 5, 3, 3, 3, 5, 3, 6, 2, 3, 9, 5$

The (absolute) frequency of the observation $3$ is $5$.

The (absolute) frequency of the observation $9$ is $1$.

Also known as

The frequency of $\omega$ is also referred to as the absolute frequency of $\omega$, so as to distinguish it explicitly from relative frequency.

When $\omega$ is a class interval, the frequency of $\omega$ is referred to as a class frequency.

Also see

• Definition:Relative Frequency

• Results about frequency in the context of descriptive statistics can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): frequency: 2.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): frequency: 2.
• 2011: Charles Henry Brase and Corrinne Pellillo Brase: Understandable Statistics (10th ed.): $\S 2.1$
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): absolute frequency
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): absolute frequency