<Li> Y is the cumulated proportion of the income variable, for k = 0,..., n, with Y = 0, Y = 1 . </Li> <Li> Y should be indexed in non-decreasing order (Y> Y) </Li> <P> If the Lorenz curve is approximated on each interval as a line between consecutive points, then the area B can be approximated with trapezoids and: </P> <Dl> <Dd> G 1 = 1 − ∑ k = 1 n (X k − X k − 1) (Y k + Y k − 1) (\ displaystyle G_ (1) = 1 - \ sum _ (k = 1) ^ (n) (X_ (k) - X_ (k - 1)) (Y_ (k) + Y_ (k - 1))) </Dd> </Dl>

What does it mean if the gini coefficient for any given society is rising over time