A household is classified into a given decile group on the basis of available income (or expenditure) per capita in that household in relation to the distribution of income across the population. For his purpose, all households are weighted, listed according to the increasing value of available income (or expenditure) per capita (from the smallest to the largest). This list is then divided into ten equal parts. The first decile group consists of 10% of persons with the lowest income (or expenditure), while the tenth decile group – 10% of persons with the highest income (or expenditure).