On continuity of integration methods for AUC. A note.

A lack of monotonicity and discontinuity of some integration methods for AUC, as a function of measured concentration, is demonstrated. Hybrid methods consisting of either parabolas-through-the-origin or the alpha-function method followed by the log-trapezoidal method were found to be discontinuous at the switching point. The stable piecewise third-order polynomial method appeared to be nonmonotonic as well as discontinuous.