Existing studies, however, count inconclusive responses as correct (i.e., “not errors”) without any explanation or justification. These inconclusive responses have a huge impact on the reported error rates. In the Ames I study, for example, the researchers reported a false positive error rate of 1 percent. But here’s how they got to that: of the 2,178 comparisons they made between nonmatching cartridge cases, 65 percent of the comparisons were correctly called “eliminations.” The other 34 percent of the comparisons were called “inconclusive”, but instead of keeping them as their own category, the researchers lumped them in with eliminations, leaving 1 percent as what they called their false-positive rate. If, however, those inconclusive responses are errors, then
the error rate would be 35 percent. Seven years later, the Ames Laboratory conducted another study, known as Ames II, using the same methodology and reported false positive error rates for bullet and cartridge case comparisons of
less than 1 percent. However, when calling inconclusive responses as incorrect instead of correct, the overall error rate skyrockets to 52 percent.