1. A method for generating a compound probability that product ion spectral data matches a candidate sequence in a sequence database by random, the product ion spectral data having been generated by a non-ergodic process, and the method comprising the steps of: (a) acquiring first product ion spectral data; (b) preprocessing the first product ion spectral data; (c) determining product ion abundance values and product ion mass-to-charge ratio values for each of a plurality of peaks from the pre-processed first product ion spectral data; (d) utilizing the product ion abundance values to determine an intensity probability distribution, the intensity probability distribution representing a first probability that the product ion spectral data was generated at random; (e) utilizing the mass-to-charge ratio values of the product ions to determine a fragment probability distribution, the fragment probability distribution representing a second probability that the product ion spectral data was generated at random; and (f) determining the compound probability based on the intensity probability distribution and the fragment probability distribution, the probability representing a probability that the generated product ion spectral data matches a candidate sequence in the sequence database at random.