Use of a computer to provide a statistical evaluation of effluent sampling programme data

The use of a simple computer program to analyse data from an effluent sampling programme for the purpose of identifying anomalous results is discussed. The computer program, called 'Analytical Data Evaluator' (ADE), performs a series of statistical tests on each data point generated by the effluent sampling programme and locates all data, which because of an unusual characteristic, warrant further investigation. A specific data point is identified as an anomaly if it fails to meet acceptance criteria established for any of the statistical tests that are applied to the data. The acceptance criteria are composed of limits based upon (1) facility operational performance requirements, and (2) parameters selected by the user to provide the desired level of sensitivity of anomaly detection. The ADE program generates a brief but descriptive report of anomalous data identifications and provides an auditable means for resolving the anomalies detected. The program is intended to be used by environmental monitoring staff members to assess the operational performance of the facility, effluent sampling programme and analytical laboratory. The principal benefits obtained from use of the program are the reduction in unexplained unusual sampling results and a reduction in the time spent by the staff in reviewing the sample data. (author)