A method of generating a frequency distribution of scores for a particular experimental condition, wherein the scores relate to random identifications of biological molecules, the method comprising: a) generating mass data for the particular experimental condition for known biological molecules in a biological molecule database; b) generating mass data of a hypothetical biological molecule for the experimental condition; c) comparing the data generated in step (b) with the data generated for each known biological molecule in step (a); d) calculating a score for each comparison in step (c), wherein the score is a function of similarity between the data generated in step (a), which corresponds to a particular known biological molecule, and the data generated in step (b); e) selecting a score from the scores calculated in step (d), wherein the selected score corresponds to the comparison which denotes a high degree of similarity between the data generated in step (a) and the data generated in step (b); f) repeating steps (b) through (e) with different hypothetical biological molecules until a sufficient quantity of scores are selected; and g) determining the frequency of selecting each score and generating therefrom a frequency distribution of scores.