Subset gene structure and the corresponding estimated concentrations. (A) shows a 2-variant "subset" gene structure, where the genomic composition of variant 1 is a subset of variant 2. (B) shows the estimated concentrations of the two variants for 20 different initial values using Wang et al.'s method . Each line indicates estimated concentrations with one set of initial value; all are globally optimal solutions that give the same RSS. See  for details.