4.1 An accountability and quality control system is established by laboratory management to improve the quality of its results. It provides documented records which serve to assure users of the laboratory's services that a specified level of precision is achieved in the routine performance of its measurements and that the data reported were obtained from the samples submitted. The system also provides for: early warning to analysts when methods or equipment begin to develop a bias or show deterioration of precision; the protection and retrievability of data (results); traceability and control of samples as they are processed through the laboratory; good communication of sample information between submitters, analysts, and supervision; and information on sample processing history. This guide describes such a system. Other accountability and quality control programs can be developed. Such programs can be equivalent to the program in this guide if they provide all of the benefits mentioned above.