title: Using the confidence interval of the mean to detect systematic errors in one analytical run.
abstract: BACKGROUND
  The commonly used Westgard control rules to detect systematic errors in one analytical run are far from perfect. Mean rules are more effective, but are in little use. We propose using a variant of mean rules, where we compare the confidence interval of the mean directly with the allowable systematic error.
  
  
  METHODS
  Probabilities of false rejection and error detection were calculated using standard Normal distribution functions.
  
  
  CONCLUSIONS
  Confidence interval of the mean rules are more flexible and are more easy to practise than the traditional mean rules. They outperform the commonly used Westgard rules if more than one control specimen is analysed in each run.
authors.affiliation: Department of Clinical Chemistry, Trondheim University Hospital, Trondheim, Norway. arne.aasberg@stolav.no
authors.forename: Arne
authors.initials: A
authors.lastname: Asberg
authors.forename: Bjørn
authors.initials: B
authors.lastname: Bolann
authors.forename: Gustav
authors.initials: G
authors.lastname: Mikkelsen
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000706:statistics & numerical data*; D016001:Confidence Intervals; D003951:Diagnostic Errors / Q000517:prevention & control*; D005189:False Positive Reactions; D006801:Humans; D011786:Quality Control; D015203:Reproducibility of Results; D013223:Statistics as Topic