Groups charged with the interpretation of international marine monitoring data have historically found it necessary to employ arbitrary criteria for the inclusion of field data in their assessments, based upon disparate and incomplete quality assurance information. It is anticipated that moves to require QA information to be directly associated with field data in international databanks, to establish quantified programme objectives and designs with appropriate statistical power, and the firm establishment of international laboratory performance studies (such as the QUASIMEME programme) will improve both the information available to assessment groups and the reliability of their conclusions.