CMT Laboratory Quality Control and Management 5

Question 1

In a single run, Level 1 control is at +2.3 SD and Level 2 control is at -2.4 SD. Which rule is violated, and what error does it indicate?

Accepted Answer

R-4s, random error

Answer

R-4s is violated when the gap between two controls in a run is more than 4 SD, which signals random error.

Question 2

Repeated runs of a reference material give 4.1, 4.2, 4.1, and 4.2 mmol/L, but the true value is 5.0 mmol/L. How do you describe this method?

Accepted Answer

Precise but inaccurate

Answer

The results agree closely with each other (precise) but are far from the true value (inaccurate, biased).

Question 3

Under CLIA, how often must calibration verification be done at minimum for most quantitative tests?

Accepted Answer

Every 6 months

Answer

CLIA requires calibration verification at least every 6 months, and also after major maintenance or reagent lot changes.

Question 4

A patient's bilirubin result is above the analyzer's analytical measurement range (AMR). What should the technologist do?

Accepted Answer

Dilute the specimen with an approved diluent, re-run it, and multiply by the dilution factor

Answer

Results above the AMR are unreliable, so the sample is diluted within validated limits and the result is corrected for the dilution.

Question 5

An assay has an allowable total error (TEa) of 10%, a bias of 2%, and a CV of 2%. What is its sigma metric?

Accepted Answer

4

Answer

Sigma = (TEa - |bias|) / CV = (10 - 2) / 2 = 4.

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