1.2 Displaying Distributions of Categorical Data

Visualising Categorical Data


  • The number of times a particular value or category occurs is known as the frequency. This is often used as the basis for displaying and analysing categorical data.


In the following dataset of colours:

Red Red Blue Red

The frequency of each colour is:

Red: 3

Blue: 1


  • The proportion of the total data points which belong to a particular group is known as the percentage.
  • This can be calculated using the formula:
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1.1 Overview of Data Types

Categorical Data

  • Data which is sorted into groups is considered categorical data

Nominal Data

      • Categorical data with no hierarchy (i.e. one category is not “greater than” another) is considered nominal data


Eye colour can be considered a nominal data type as the data (each person’s eye colour) can be placed into groups and there is no hierarchy

Ordinal Data

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