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Alternative approaches for analyzing sampling and analytical methods.

Bartley DL; Fischbach TJ
Appl Occup Environ Hyg 1993 Apr; 8(4):381-385
Alternative approaches for analyzing errors in evaluations of sampling and analytical methods were described. The standard criterion for determining the acceptability of a sampling or analytical method applied by NIOSH and OSHA is that the overall single sample inaccuracy must fall within +/-25% of the reference value at the 95% confidence level. These criteria have been found to be satisfactory for making legally defensible determinations. Experimental evaluations using a reference sampler were required to determine whether a proposed sampling and analytical method meets the NIOSH/OSHA criterion. Alternative approaches for evaluating the accuracy and precision of respirable aerosol samplers were presented. These consisted of the integral control of evaluation errors (integral control), tolerance interval control, and individual or Bonferroni control techniques. The integral control approach specified a lower probability that a method will be considered unacceptable, such as 90%, than that of the NIOSH/OSHA criteria. Using this approach, a single sided 90% confidence band is established about the mean bias and imprecision of the reference samples. A method would be considered to be acceptable if its bias and relative standard deviation fall outside this band. The tolerance interval control approach was based on specifying a range of bias and imprecision that is acceptable and these parameters of the considered method must fall within this range. The individual control approach assumed that the bias and imprecision of the proposed method equal their individual upper 95% confidence limits. A proposed sampling or analytical method was considered acceptable if its bias and imprecision individually fall within these limits.
NIOSH-Author; Air-monitoring; Industrial-hygiene; Statistical-analysis; Mathematical-models; Quality-standards; Equipment-reliability; Sampling-methods
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Applied Occupational and Environmental Hygiene
Page last reviewed: September 25, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division