Limits of quantitation for laboratory assays

Research output: Contribution to journalReview articlepeer-review

6 Scopus citations


A common problem with laboratory assays is that a measurement of a substance in a test sample becomes relatively imprecise as the concentration decreases. A standard solution is to establish lower limits for reliable measurement. A quantitation limit is a level above which a measurement has sufficient precision to be reliably reported. The paper proposes a new approach to defining the limit of quantitation for the case where a linear calibration curve is used to estimate actual concentrations from measured values. The approach is based on the relative precision of the estimated concentration, using the delta method to approximate the precision. A graphical display is proposed for the assessment of estimated concentrations, as well as the overall reliability of the calibration curve. Our research is motivated by a clinical inhalation experiment. Comparisons are made between the approach proposed and two standard methods, using both real and simulated data.

Original languageEnglish (US)
Pages (from-to)63-76
Number of pages14
JournalJournal of the Royal Statistical Society. Series C: Applied Statistics
Issue number1
StatePublished - 2005
Externally publishedYes


  • Calibration
  • Delta method
  • Detection limit
  • Limit of quantitation
  • Linear regression

ASJC Scopus subject areas

  • Statistics and Probability
  • Statistics, Probability and Uncertainty


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