Collusion or falsification of results in PT: why does it happen and how can it be prevented?

Proficiency testing is an essential tool, which laboratories may use to demonstrate their competence, enabling them to evaluate their performance for specific measurements, tests or calibrations by comparison with results of other laboratories. The pressure therefore to consistently perform ‘well’ in proficiency tests may lead participants to consider colluding with other labs or falsifying data, in order to ensure a high standard of performance. The requirements for the accreditation of proficiency testing schemes to the ISO/IEC 17043 standard place a responsibility on the providers of proficiency testing to consider the possibility of collusion within their schemes and to take measures to discourage or prevent it. A survey of proficiency testing providers has been performed to gather a range of opinions on the ‘state’ of collusion within their schemes. The options available to providers for prevention of collusion and the difficulties of detection are also discussed.