# Types of data

## Key points

• Types of data include continuous, discrete and categoric.
• Classifying a variable as a particular type of data is important when considering how to present the data.
• Data can be presented in a number of ways, which depends on the type of variable and the uses.

How do scientists collect data to help answer questions?

Scientists collect data from carrying out experiments and investigations.

### Video

Watch this video about how to identify continuous and discrete data.

## Types of data

In science, investigations involve the collection of data. The data collected can be or .

Data collected can be:

• - numeric data can have any value within a range. Examples include time, height and temperature.
• - numeric data that can only have certain values. Examples include shoe size, number of people in a room and the number of marks on a test.
• - the data are words. Examples include colour such as ‘red’ or ‘blue’, and how an object feels like, eg: ‘rough’ or ‘smooth’.

During an experiment, the effect of one on another is tested. There are three types of variable:

• Independent - a variable that is changed during an experiment.
• Dependent - a variable that is measured or tested during an experiment. This depends on the independent variable.
• Control - a variable, other than the independent variable, that could affect the dependent variable. A control variable is something you keep the same.

The variable that is measured - the dependent variable - is often measured as continuous data, but this is not always the case.

• For example, in an experiment to find out how the temperature of a liquid decreased over time, temperature is the dependent variable and is continuous.
• But in an investigation into eye colour, the number of people is the dependent variable and the data is discrete.

Independent variables can be categoric or continuous.

• An example of categoric data would be ‘choice of food for lunch’ and 'counting the number of people who chose certain foods'.
• An example of continuous data would be 'temperature': when changing the temperature of water, see how quickly sugar dissolves into it.

True or false?

Dependent variables can be continuous or discrete.

True.

## How to present data

The method of presentation depends on:

• The type of variable.
• The reason for presenting the data, eg to sort/ compare/ show a pattern.

Below are ways of presenting data:

Ways of presenting dataUses
TableTo show data in an order, eg biggest to smallest number. Also used to record results during an experiment.
To find a link between variables. Both variables are quantitative and could be discrete or continuous. A scatter graph is a line graph but without the line joining the points.
To show how the dependent variable affects the independent variable. Both variables are continuous. The points are joined with a line of best fit, which is straight or a smooth curve.
To compare sets of data. The independent variable is usually discrete and the dependent variable is quantitative.
To show proportions of a total. The independent variable is discrete or categoric. Often used when showing percentages of data.

The way in which data is presented depends on the reason for presenting data, and what else?

The type of variable.