56  Frequency Table

56.1 Definition

The Frequency Table displays the relative and absolute frequencies (columns) for different items or categories (rows) of a univariate dataset that consists of qualitative observations.

The Frequency Table lists all categories that occur in the dataset. For each category, the table displays two values: the absolute frequency (the count of how many times that category appears) and the relative frequency (the proportion of observations belonging to that category). The categories are typically sorted by frequency, allowing the user to quickly identify which categories are most and least common. The same information is displayed graphically in the Frequency Plot (Chapter 55), where each category corresponds to a bar and the bar height represents the absolute frequency.

56.1.1 Absolute Frequency

The section labeled “Absolute Frequency” of the Frequency Table corresponds to the counts of each category.

56.1.2 Relative Frequency

The section named “Relative Frequency” corresponds to the Absolute Frequencies divided by the number of observations of the dataset.

56.2 R Module

56.2.1 Public website

The Frequency Table can be found on the public website:

56.2.2 RFC

The Frequency Table is available in RFC under the menu “Descriptive / Histogram & Frequency Table”.

If you prefer to compute the Frequency Table on your local computer, the following code snippet can be used in the R console:

x <- c('A','B','A','A','B','C','C','A','B','A','A','B','C','C','A','B','A','A','B','C','C')
sort(table(x),T) #absolute frequencies
sort(table(x),T) / sum(table(x)) #relative frequencies
x
A B C 
9 6 6 
x
        A         B         C 
0.4285714 0.2857143 0.2857143

To create a Frequency Table, the R code first computes a frequency table with the table function (there is no external library required). The result of this function is used as an input in sort which can be used to order the frequencies in ascending or descending order.

56.3 Purpose

The Frequency Table shows how often each category occurs in the (qualitative) univariate dataset. The absolute frequencies are ordered from high to low because this allows the user to quickly assess the ranking of each category.

56.4 Pros & Cons

56.4.1 Pros

The Frequency Table has the following advantages:

  • It is easy to compute.
  • It is relatively easy to interpret.
  • Many readers are familiar with Frequency Tables.

56.4.2 Cons

The Frequency Table has the following disadvantages:

  • The amount of information that is conveyed is limited.

56.5 Example

The following worked example shows a Frequency Table (absolute and relative frequencies) for the sample dataset used in the R Module.

Category Absolute Frequency Relative Frequency
A 9 0.4286
B 6 0.2857
C 6 0.2857