CMLA Quality Control & Assurance in Laboratory Practices 2

Question 1

When a control value falls outside the 2s warning limit but within the 3s rejection limit, which Westgard rule has been violated?

Accepted Answer

1-2s warning rule

Answer

The 1-2s rule is a warning rule triggered when one control value exceeds ±2 standard deviations, signaling the need for increased scrutiny.

Question 2

Which type of error causes all control values to shift consistently in the same direction from the mean?

Accepted Answer

Systematic error

Answer

Systematic error (bias) shifts results consistently in one direction, often due to reagent lot changes, calibration drift, or temperature issues.

Question 3

A laboratory's Levey-Jennings chart shows the last six consecutive control values trending steadily upward. Which Westgard rule does this violate?

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 bias.

Question 4

What is the primary purpose of running both normal and abnormal control levels in the laboratory?

Accepted Answer

To detect errors across the reportable range

Answer

Running controls at multiple levels ensures the method performs accurately across the entire clinically relevant range, not just at one concentration.

Question 5

Which document defines acceptable performance specifications for a laboratory test, including allowable total error?

Accepted Answer

Method validation protocol

Answer

A method validation protocol defines performance specifications such as precision, accuracy, and allowable total error before a test is implemented.

(CMLA) Certified Medical Laboratory Assistant Practice Test

(CMLA) Certified Medical Laboratory Assistant Practice Test

CMLA Quality Control & Assurance in Laboratory Practices 2