Measures of Dispersion for Ungrouped Data
Frequency
The number of times a value or category occurs in a data set.
| English | Frequency |
|---|---|
| Bahasa Melayu | Kekerapan |
| 中文 | 频数 |
How it is used
In a survey of shoe sizes, if size 5 is recorded 8 times, its frequency is 8. Multiplying each size by its frequency and dividing by the total, Σfx / Σf, gives the mean.
Where it shows up in SPM
In Measures of Dispersion and Central Tendency for ungrouped data, and in Statistics generally. It labels the f column of a frequency table, used with Σfx and Σfx² to find the mean, variance and standard deviation in Paper 2.
Don't confuse it with
Open the chapter: Measures of Dispersion for Ungrouped Data →
Frequently asked questions
How does frequency help me find the mean?
For data in a frequency table, the mean is Σfx / Σf, where f is the frequency of each value x. Multiplying by frequency saves you from listing every repeated value, and Σf gives the total number of data items.
What is the difference between frequency and relative frequency?
Frequency is the plain count of how many times a value occurs. Relative frequency divides that count by the total number of data, giving a proportion between 0 and 1 that can also be written as a percentage or used as an estimate of probability.