1. A method for determination of threshold values of signatures composing an assay, each signature enabling detection of a target, the method comprising: providing an assay, said assay comprising signatures, said signatures enabling detection of a target, and for each signature: determining a probability density function (PDF) of negative samples in the assay; based on the determined PDF of negative samples, determining a false positive rate curve; generating a calibration curve of assay response parameter values versus concentration; generating a plot of false positive rate versus the limit of detection (LOD); selecting a LOD such that a desired false positive rate is obtained; and determining the threshold corresponding to the selected LOD.