On a Levey-Jennings chart, you identify the Level 1 quality control (QC1) value exceeds the mean by a positive 3-standard deviation (+3SD). The Level 2 quality control (QC2) value exceeds the mean by a negative 3-standard deviation (-3SD) within the same run. What is the most likely cause of this error?Group of answer choicesThe reagent pack has deteriorated and needs to be replaced for a new oneThe lamp in the spectrometric compartment of the analyser has worn off over timeQC1 and QC2 were swappedQC materials were left overnight at room temperature
Question
On a Levey-Jennings chart, you identify the Level 1 quality control (QC1) value exceeds the mean by a positive 3-standard deviation (+3SD). The Level 2 quality control (QC2) value exceeds the mean by a negative 3-standard deviation (-3SD) within the same run. What is the most likely cause of this error?Group of answer choicesThe reagent pack has deteriorated and needs to be replaced for a new oneThe lamp in the spectrometric compartment of the analyser has worn off over timeQC1 and QC2 were swappedQC materials were left overnight at room temperature
Solution
The most likely cause of this error is that QC1 and QC2 were swapped. This is because both QC1 and QC2 values are exceeding the mean by 3 standard deviations but in opposite directions (one positive and one negative) within the same run. This suggests that the controls were likely switched when they were run. If the reagent pack had deteriorated or the lamp in the spectrometric compartment of the analyser had worn off over time, it would likely affect both QC1 and QC2 in the same direction. Similarly, if QC materials were left overnight at room temperature, it would also likely affect both QC1 and QC2 in the same direction.
Similar Questions
Which one of the following statements regarding internal quality control (IQC) is INCORRECT?Group of answer choicesOn a Levey-Jenning chart of 5 consecutive runs using the levels 1 and 2 control materials (QC1 and QC2), one QC2 data falls between the 2- and 3-standard deviation (+/-2SD and +/- 3SD) limits. All previous QC values are under the +/- 2SD limits. It is valid to report the patient results in this instance.Repeatedly running the IQC will rectify an analytical issue associated with systematic errorSystematic error has a proportional bias off the target value.A possible cause of random error is due to failure in the automated sampling system.
An example of shift you would observe in a Levey-Jennings quality control chart is due to a lot number change of the reagent.Group of answer choicesTrueFalse
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What is the lower outlier if Q1 is 26 and Q3 is 157?
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