A series of non parametric tests validated the digitized distortion model and indicated that the Paired Comparison Method was superior to the Standard Comparison Method.

For the standard analytical method, the series of standard solution for the determination of As, se and Hg in water by atomic fluorescence spectrophotometry must be prepared for every test.

The real test, however, of the method would be to apply it to a variety of analogue controllers of both the standard and series structures.