Numerical Variable

A numerical variable measures a quantity with numbers on which arithmetic genuinely makes sense, such as height in centimetres, temperature, or number of clicks. The difference between values carries real meaning: 20 clicks is twice 10 clicks.

Numerical variables split into discrete (whole counts, like the number of children) and continuous (any value in a range, like weight). You summarise them with measures such as the mean, median, and standard deviation, and visualise them with histograms or boxplots. Beware of ID-like numbers — a customer number is stored as digits but is really a label, and averaging it is a classic beginner error.