MLS Quality Assurance & Standards 2

Question 1

A Levey-Jennings chart shows 6 consecutive control values all falling on the same side of the mean. Which Westgard rule is violated?

Accepted Answer

10x rule

Answer

The 10x rule is violated when 10 consecutive control values fall on the same side of the mean, indicating systematic error; 6 in a row triggers the warning precursor.

Question 2

Which term describes the ability of an analytical method to measure only the analyte of interest without interference from other substances?

Accepted Answer

Specificity

Answer

Specificity (or selectivity) refers to the method's ability to measure only the target analyte without cross-reactivity from other compounds.

Question 3

A laboratory's troponin assay has a coefficient of variation (CV) of 15% at a low concentration. This primarily indicates a problem with:

Accepted Answer

Precision

Answer

CV measures imprecision; a high CV at low concentrations indicates poor reproducibility (precision) of the assay at that level.

Question 4

CLIA '88 regulations require that proficiency testing samples be tested:

Accepted Answer

By the same method used for patient samples

Answer

CLIA '88 mandates that PT samples be tested using the same routine methods, instruments, and personnel as patient samples to ensure valid assessment.

Question 5

Which type of error is detected by calculating the mean of control values over time?

Accepted Answer

Systematic error

Answer

Systematic error causes a consistent bias (shift or trend) that is detected by monitoring the mean of control values over multiple runs.

(MLS) Medical Laboratory Scientist Practice Test

(MLS) Medical Laboratory Scientist Practice Test

MLS Quality Assurance & Standards 2