Low, middle and high incomes

The distinction between low, middle and high incomes is based on quartile groups. Persons are arranged in ascending order of standardised disposable household income and subsequently subdivided into four groups of equal size (quartile groups). The low income group comprises the 25 percent of persons with the lowest incomes (first or lowest quartile). The middle income group comprises the second and third quartiles and the high income group comprises the fourth (or highest) quartile.