Detection limits and goodness-of-fit measures for the two-component model of chemical analytical error

Machelle D. Wilson, David M Rocke, Blythe Durbin, Henry D. Kahn

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


The utility of analytical chemistry measurements in most applications is dependent on an assessment of measurement error. This paper demonstrates the use of a two-component error model in setting limits of detection and related concepts and introduces two goodness-of-fit statistics for assessing the appropriateness of the model for the data at hand. The model is applicable to analytical methods in which high concentrations are measured with approximately constant relative standard deviation. At low levels, the relative standard deviation cannot stay constant, since this implies vanishingly small absolute standard deviation. The two-component model has approximately constant standard deviation near zero concentration, and approximately constant relative standard deviation at high concentrations, a pattern that is frequently observed in practice. Here we discuss several important applications of the model to environmental monitoring and also introduce two goodness-of-fit statistics, to ascertain whether the data exhibit the error structure assumed by the model, as well as to look for problems with experimental design.

Original languageEnglish (US)
Pages (from-to)197-208
Number of pages12
JournalAnalytica Chimica Acta
Issue number2
StatePublished - May 3 2004


  • Chemical analytical error
  • Goodness-of-fit
  • Limits of detection
  • Two-component error model

ASJC Scopus subject areas

  • Biochemistry
  • Analytical Chemistry
  • Spectroscopy
  • Environmental Chemistry


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