Reliability of measurement uncertainty estimates for forensic analyses: evidence from recent proficiency tests

The ability of forensic laboratories to reliably estimate the uncertainty of their reported results is assessed by means of data from recent proficiency tests in which participants reported both their results and the associated uncertainties. Topics covered include the determination of blood alcohol, breath alcohol, and controlled substances-services commonly provided by forensic laboratories. It is seen that a statistically significant number of laboratories underestimate their own uncertainties, based on the incidence of the laboratories' own reported coverage intervals failing to include the participant mean or assigned concentration of the test material.