Patent ID: 7469186

Claim:
One or more computer-readable media comprising computer-executable instructions for performing a method to calculate concentration of a substance in a test sample, the method comprising: after a second derivative is calculated for a standard sigmoid curve, finding a first point on the standard sigmoid curve via the second derivative of the standard sigmoid curve and designating the first point as a first bound; finding a second point on the standard sigmoid curve via the second derivative of the standard sigmoid curve and designating the second point as a second bound; determining a usable portion of the standard sigmoid curve as a plurality of points on the standard sigmoid curve between the first bound and the second bound; for at least one observation of a metric for the test sample, determining whether the at least one observation is within the usable portion of the standard sigmoid curve; and responsive to determining that the at least one observation is within the usable portion, calculating a concentration of the substance based on a location of the observation on the standard sigmoid curve.