A computer program to promote understanding of the monitoring method evaluation guidelines used at NIOSH

A computer-based training program has been devised to promote better understanding of the recently revised National Institute for Occupational Safety and Health (NIOSH) test guidelines applicable to methods requiring on-site sample collection and laboratory sample analysis of airborne toxic substances. A statistics section explains the basis of the NIOSH accuracy criterion (NAC); an experiments section provides details on the evaluation experiments; and a calculations section calculates method statistics based on data entered by the user. The statistics section graphically explains concepts such as the NAC and limit of detection, allowing the user to experiment with some parameters to see how the results are affected. This section also provides background material to show how some of the performance criteria evolved. The experiments section provides a summary of the experiments used to generate the data for method evaluation. The calculations section has several screens that work like customized spreadsheets for the entry of data collected during the laboratory evaluation of a method. A separate screen then calculates the precision (relative standard deviation) of analytical results at each of four concentrations, tests to see if the precision values are statistically homogeneous, and combines the homogeneous data for calculation of the relative standard deviation. It does the same for bias, and combines the precision with method bias to arrive at an estimate of method accuracy. Other screens in the calculations section facilitate the determination of method limit of detection and sample storage stability.