A simulated electrophoretic trace is prepared by first obtaining an input file containing an input base sequence comprising a string of letters (A, C, G and/or T) in an order corresponding to the input base sequence, and then modifying the input file using one or more functions to take into account perturbations associated with (1) changes in peak intensity as a function of base number; (2) peak shape as a function of base number; (3) peak skew; (4) spacing between peaks; (5) background; (6) noise; (7) spectral cross-talk; (8) instrumental effects and/or (9) gel electrophoresis effects to produce a modified file representing a simulated electrophoretic trace. The method may be performed using a specially adapted apparatus.