Clinical Assessment Methods Flashcards

On a Levey-Jennings chart, one control exceeds +3 SD. Which Westgard rule is violated?

Answer: 1-3s

A single control beyond ±3 SD violates the 1-3s rule, indicating random error.

Two consecutive control values exceed +2 SD on the same side of the mean. This suggests:

Answer: Systematic error

The 2-2s rule detects systematic error such as calibration shift.

Ten consecutive control values fall on the same side of the mean. This pattern is called a:

Answer: Shift

An abrupt sustained change to one side of the mean is a shift (10x rule).

A gradual, continuous movement of control values in one direction over several days is most likely caused by:

Answer: Deteriorating reagent or lamp

Trends indicate progressive changes like reagent or light source deterioration.

Which describes external quality assessment through proficiency testing?

Answer: Analyzing unknown samples from an outside agency and comparing results to peers

PT compares lab results on blind samples against peer groups, as required by CLIA.

Under CLIA, nonwaived quantitative tests generally require at minimum how many levels of control per day of testing?

Answer: Two

CLIA requires at least two control levels each day for most quantitative tests.

The difference between the mean of measured results and the true value represents:

Answer: Accuracy bias (systematic error)

Bias is the systematic deviation of results from the true value.