Since Y should be an inter-array technical replicate of X, there must be no differentially phosphorylated peptides on Y in comparison to X. This is achieved in two different ways. For θ percent of the peptides, the algorithm introduces an amount of perturbation as follows. It calculates an average background-corrected intensity value, abct, for a peptide xt. It then selects an arbitrary ri,j∈R, where ri,j is not differentially phosphorylated in comparison to xt using a fold-change of T and confidence level of α. The algorithm adds ri,j as the l measurements for within-array replicates of the tth peptide in Y (i.e., as yt). Variables w and v are the bounds for determining whether the peptide represented by ri,j is not differentially phosphorylated. For the other 100-θ percent of peptides, the algorithm selects an arbitrary peptide ri,j∈R, where ri,j is not significantly different from the mean of xt, and assigns it to yt. In both cases if such an ri,j∈R cannot be found, yt is set to the original xt.