8 laboratories took part in a proficiency test regarding low levels of Pb and Bi in two steels. 9 sets of data were sent in, meaning that one laboratory contributed with two sets of data. Each set of data was given an anonymous number. The analytical techniques used were GFAAS (Graphite Furnace Atomic Absorption Spectroscopy), ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) and GD-MS (Glow Discharge-Mass Spectrometry). A statistical evaluation was carried out in order to find outlying values by applying the Cochran`s test and the Grubb`s test iteratively.