Ridits provide a method for replacing the categories of an ordinal variable by scores between 0 and 1. Suppose that a variable has five ordered categories: ‘very low’, ‘low’, ‘medium’, ‘high’, and ‘very high’, with respective frequencies 16, 24, 36, 22, and 2 (totalling 100). The ridits would be (i.e. 0.08, 0.28, 0.58, 0.87, and 0.99). In this case the category ‘very high’ is given a more extreme score than the category ‘very low’ reflecting its comparative rarity.