 In the Cambridge Structural Database of small-molecule structures, more than 95% of the 500,000+ crystals have an R-factor lower than 0.15, and 9.5% have an R-factor lower than 0.03.Crystallographers also use the Free R-Factor (formula_5)  to assess possible overmodeling of the data.formula_5 is computed according to the same formula given above, but on a small, random sample of data that are set aside for the purpose and never included in the refinement.