Types of data

Numerical data

Numerical data is quantitative and can be counted, ordered and measured.

Numerical data can be split into two categories: continuous and discrete.

Continuous Data

A data set is said to be continuous if the observed values may take on any value within a finite or infinite interval. 

Examples

Height, weight, temperature, the time taken to run $100$100 metres.

Do you notice how all these examples could be anywhere on a scale interval and could even be fractions? For example, it might be $25.3$25.3 degrees or a man might be $182.13$182.13cm tall. 

Discrete Data

A data set is said to be discrete if the numerical values can be counted but are distinct and separate from each other. They are often (but not always) whole number values.

Examples

The number of goal scored in a game, the number of people in a class, the number of pets people have.

Do you notice how all these examples have distinct values? For example, you couldn't score $2.5$2.5 goals in a game of soccer or own $\frac{1}{4}$14​ of a dog so there is no continuity between the scores.

However, in some tournaments, half a point is awarded for a draw. In this case, there could be a score of $2.5$2.5, but there still could not be a score of $2.25$2.25 or $2.75$2.75 so the data is still discrete.

Categorical data

Categorical data is non-numerical. In other words, it describes the qualities or characteristics of a data set. It is also called qualitative data.

There are two types of categorical data: ordinal and nominal.

Ordinal data

A set of data is said to be ordinal if the values can be counted and ordered but not measured.

Example

Rating scales are examples of ordinal data. The finishing places in a race are another example of ordinal data. Think about it- the positions in a race can be ordered or ranked. Finishing first means you were faster than the person who came second and the person who finished eighth was slower than the person who finished sixth. However, the differences between the finishing times may not be the same between all competitors. Check out the picture below. The times between first and second will be really close- maybe less than half a second. However, the time between second and third may be more than a second. There is not a fixed interval.

Nominal data

Nominal basically means name. In other words, data is split up based on different names or characteristics. Nominal data may be the names of countries you have visited or your favourite colours. We could assign these different characteristics a number where the numbers are simply labels. In other words, you are giving numerical data numerical labels. You can count but not order or measure nominal data. 

Example

We could divide a group  of people into males and females. We could also use "male" and "female" as our two categories to count how many men and women there were in the group. 

Worked Examples

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