La mesure des inégalités. Un point de vue de statisticiens

The example of inequalities among incomes makes it possible to present a critical analysis of the technical paraphenalia statisticians have to measure inequalities. The ratio between the meansof various social groups, the coefficients of dispersions or the synthetic indicators of concentration give various possibilities to describe the gaps between incomes among one population, or two subpopulations, in various ways. The least precaution to take is to define the concepts as well as the units between which comparisons are being made, with precision. If general reports can usually be established, the diversity of points of view as well as the existence of various instruments of measure do not always give the possibility to get the same appraisal of the range of inequalities. Things get more complex when, coming to the various fields of social life, one tries to establish a scale of « standards of living », to compare the « ways of living ». The fields which are more qualitative than incomes raise special problems. But above all, the combining of various indicators concerning various fields is technically more difficult and even raises fundamental questions : how to build only one scale of reference, how to reckon the comparative «weights» of various fields ? Last, beyond the problems of measure and combinations, thinking about the difference between inequalities as they are and inequalities as they are felt, about the notion of justice (which that of inequality implicity refers to), about the necessary conflicts and cooperations and on the specificity of the groups, which cannot always be reduced to inequalities, all this leads to the conclusion that to understand social reality on must go beyond the perspective of inequalities.