Given two Qini curves, \(Q_a\) and \(Q_b\), and a maximum spend \(\bar B\), get an estimate of the integrated difference \(\int_{0}^{\bar B} (Q_a(B) - Q_b(B))dB\).
integrated_difference(object.lhs, object.rhs, spend)An estimate of the area between the two curves along with standard errors.
A maq object \(Q_a\) to subtract from.
A maq object \(Q_b\) to subtract with.
The spend level \(\bar B\).