Quantitative and Qualitative variables

This section explores classification of variables or data. In statistics data is a collection of observations or measurements of variable. The classification of variables depends on whether their observations can be written down as a number.
In this section we shall explore two types of variables; the quantitative and qualitative variables.

• Quantitative variables; These are variables associated with numerical observations.
• Qualitative variables; These are variables associated with non-numerical observations.

In the following example we’re going to look at different variables and decide whether their observations are numerical or not.
The following table shows observations for the collar size variable.

In the table above the observations of collar size are numerical. Since we can give a number for the size of collar we can therefore refer to this variable as a quantitative variable.
The following table shows observations for the height variable.

In the table above the observations of height are numerical. The variable height is a quantitative variable since the observations of height are numerical.
The following table shows observations for the hair colour variable.

In the table above the observations of hair colour are not numerical. Hair colour is known as a qualitative variable since you can’t give a number to hair colour.