Statistical treatments for rapid tests with discrete measuring range

Colorimetric determination of analytes with comparators is characterized by stepwise measuring. Standard deviation as well as confidence interval are based on the distribution of measuring values. No continuous distribution of measuring values can be obtained with the use of colorimetric methods. The measuring range is cut in intervals and the measuring values show discrete distribution (measuring steps or bins). The measuring steps are nonuniformly distributed over the measuring range. This is an attempt to calculate statistical measurements for these determination methods. It is shown that adding two measuring steps to the measuring value is a quick way to check whether limit levels are exceeded. © 2000 John Wiley & Sons, Inc. Field Analyt Chem Technol 4: 270–273, 2000