title: A novel quantitative evaluation method for quality control results.
abstract: BACKGROUND
  Quality control (QC) procedures using stable control materials are important for preventing systematic errors (SEs). While the current QC methods assess QC results semi-quantitatively, we designed a novel quantitative QC procedure (QQCP).
  
  
  METHODS
  QC results were expressed as Z-scores to analyze results quantitatively. The decision values were accumulated up to 30, with three decision values per run, and were compared to rejection criteria at each run. The probability for false rejection (Pfr) and error detection (Ped) for the QQCP and Westgard multirule methods were estimated using simulated QC data with SEs ranging from 0 to 3 standard deviations (SDs).
  
  
  RESULTS
  The Pfr of the QQCP was 3.4% at the 10th run. When 2 QC materials with the same SEs (0.5 SD and 1.0 SD) were used, the Peds were 36.1% and 95.7% at run 10, respectively. When the SE of each material was greater than 1.5 SDs, the Ped reached 100% at run 10. The QQCP could detect more than 99% of errors in the 6th, 4th, 3rd, and 2nd runs for 2 QC results with 1.5, 2.0, 2.5, and 3.0 SD SEs, respectively.
  
  
  CONCLUSIONS
  The QQCP exhibited a Ped value up to 3.3-fold higher than the Westgard method. Implementation of the QQCP would satisfy the high quality goals derived from biological variations.
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea. Electronic address: wkmin@amc.seoul.kr.
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Min
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Dae-Hyun
authors.initials: DH
authors.lastname: Ko
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Cho
authors.affiliation: Department of Laboratory Medicine, College of Medicine, St. Paul's Hospital, The Catholic University of Korea, Seoul, South Korea.
authors.forename: Tae-Dong
authors.initials: TD
authors.lastname: Jeong
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Woochang
authors.initials: W
authors.lastname: Lee
authors.affiliation: Department of Laboratory Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.
authors.forename: Sail
authors.initials: S
authors.lastname: Chun
authors.affiliation: Korea Association of Health Promotion, Seoul, South Korea.
authors.forename: Han-Ik
authors.initials: HI
authors.lastname: Cho
mesh_terms: D019411:Clinical Laboratory Techniques / Q000379:methods* / Q000592:standards*; D006801:Humans; D011786:Quality Control
keywords: Probability for error detection; Quality control; Quantitative quality control procedure; Westgard multirule chart