title: Statistical inference for the within-device precision of quantitative measurements in assay validation.
abstract: Intermediate precision is one of the most important characteristics for evaluation of precision in assay validation. The current methods for evaluation of within-device precision recommended by the Clinical Laboratory Standard Institute (CLSI) guideline EP5-A2 are based on the point estimator. On the other hand, in addition to point estimators, confidence intervals can provide a range for the within-device precision with a probability statement. Therefore, we suggest a confidence interval approach for assessment of the within-device precision. Furthermore, under the two-stage nested random-effects model recommended by the approved CLSI guideline EP5-A2, in addition to the current Satterthwaite's approximation and the modified large sample (MLS) methods, we apply the technique of generalized pivotal quantities (GPQ) to derive the confidence interval for the within-device precision. The data from the approved CLSI guideline EP5-A2 illustrate the applications of the confidence interval approach and comparison of results between the three methods. Results of a simulation study on the coverage probability and expected length of the three methods are reported. The proposed method of the GPQ-based confidence intervals is also extended to consider the between-laboratories variation for precision assessment.
authors.affiliation: Division of Biometry, Department of Agronomy, National Taiwan University, Taipei, Taiwan. jpliu@ntu.edu.tw
authors.forename: Jen-Pei
authors.initials: JP
authors.lastname: Liu
authors.forename: Li-Tien
authors.initials: LT
authors.lastname: Lu
authors.forename: C T
authors.initials: CT
authors.lastname: Liao
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000706:statistics & numerical data*; D001786:Blood Glucose / Q000032:analysis; D016009:Chi-Square Distribution; D003198:Computer Simulation; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D006801:Humans; D015233:Models, Statistical; D009010:Monte Carlo Method; D015588:Observer Variation; D011336:Probability; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose