“…However, one should take into account that the EQA materials also can be noncommutable between reagent lots in the same measurement procedure, as shown for INR in this study. Therefore in such cases, if large differences between reagent lots are present, lot-specific target values should be considered to avoid giving some participants wrong evaluations (7 ). As an example: for the high INR level with a target value of 4.50 INR in survey 2/2014, one of the reagent lots (lot E) had a median INR value of 3.85 INR, which was outside the lower limit of acceptable performance (3.92 INR), meaning that at least half of the participants using this lot were evaluated as "poor."…”