What Is Discrete Data?
Discrete data can only take certain values. It can (often) be counted.
The Oxford English Dictionary defines discrete as "quantity composed of distinct units, as number, in contrast to continuous quantity or magnitude."
Real Examples of Discrete Data
A teacher collects the test scores of their class.
The test scores of the pupils are discrete data. Pupils can only get a whole number of marks. 5 marks or 8 marks make sense, but 51/8 marks does not make sense.
Different shapes have different numbers of sides.
The number of sides are discrete data. You can only have a whole number of sides. It doesn't make sense to have ½ a side.
More Real Examples of Discrete Data - Not Just Whole Numbers
From the examples above, we see that when we count a whole number of items, we get discrete data.
However, values do not need to be whole numbers to be discrete, as the following examples demonstrate.
A cake shop sells slices of cake. Each slice is an 1/8th of a cake. Customers can only buy multiples of 1/8ths of a cake.
Shoes come in different sizes. Shoe sizes usually come in whole numbers, but occasionally come in ½ sizes.