Définition
If a distribution of wages, incomes, turnover, etc. Is arranged, the quartiles are the values which divide the distribution into four equal parts.
Thus, for a distribution of wages :
- the first quartile (generally written Q1) is the wage below which 25% of the wages are situated ;
- the second quartile is the wage below which 50% of the wages are situated. This is the median ;
- the third quartile (generally written Q3) is the wage below which 75 % of the wages are situated.
In an equivalent manner, the first quartile is the wage above which 75% of the wages are situated ; the second quartile is the wage above which 50% of the wages are situated, and the third quartile is the wage above which 25% of the wages are situated.