In other words, the decomposition helps to measure the portion of changes in family income due to changes in the characteristics of the child population and those due to changes in the association between these characteristics and the income level. The decomposition is carried out for market incomes before taxes and transfers (they correspond to labour income in their vast majority, capital income being generally low for poor households), and for disposable income after social transfers. By comparing the changes in income before and after taxes and transfers, one can infer what role transfers have played in responding to changes in labour income and how this role has varied across the income distribution.