Types of data

In a nutshell

Data can be categorised as qualitative or quantitative. Within quantitative data, numerical data can be categorised as either discrete or continuous. You will be dealing with quantitative or numerical data most of the time.

Types of data

Qualitative data is data which has a non-numerical value, e.g. "eye colour", or "type of plant".

Quantitative data is data which has a numerical value, e.g. "Number of students", or "Time taken to run a race".

Example 1

A student is investigating trees. As part of the investigation, she wants to record certain information. Categorise the data she needs to collect into qualitative and quantitative data.

The student wants to collect the following data: "type of tree", "colour of leaves", "length of leaves", "circumference of tree trunk" and "height of tree".

Qualitative data - "type of tree", "colour of leaves".​

Quantitative data - "length of leaves", "circumference of tree trunk" and "height of tree".​

Quantitative or numerical data can be further categorised into discrete or continuous data.

A variable that can take any value within a given range is a continuous variable, e.g. "Time taken".

A variable that can only have specific values is a discrete variable, e.g. "Number of students in a class".

Example 2

A teacher is investigating the results from sports day. He wants to record some information for further analysis. Categorise the data required into discrete or continuous.

He wants to collect the following information: "number of students in a $$100\ m$$ race", "time taken for each student in each race", "heights of students in each race", "number of races".

Discrete data - "Number of students in a $$\text{\underline{100 m}}$$​ race", "Number of races".

Continuous data - "Time taken for each student in each race", "Heights of students in each race".​