Medical Laboratory Technician Exam Laboratory Operations and QC 2

Question 1

A Levey-Jennings chart shows a series of 6 consecutive QC results trending upward across the mean. What rule does this violate?

Accepted Answer

10-x rule

Answer

The 10-x rule is violated when 10 consecutive results fall on the same side of the mean or show a progressive trend.

Question 2

Which of the following best describes 'precision' in laboratory testing?

Accepted Answer

Reproducibility of repeated measurements

Answer

Precision refers to the reproducibility or repeatability of results when the same sample is tested multiple times.

Question 3

When performing a delta check, the laboratory compares a patient's current result to:

Accepted Answer

The previous result from the same patient

Answer

Delta checks compare a patient's current result to their previous result to detect specimen identification errors or abrupt clinical changes.

Question 4

A reagent blank is used in spectrophotometry to:

Accepted Answer

Set 100% transmittance with the solvent and reagents only

Answer

A reagent blank zeroes out absorbance contributed by reagents alone so that only the analyte of interest is measured.

Question 5

Which type of error causes all results to shift consistently in one direction from the true value?

Accepted Answer

Systematic error

Answer

Systematic error (bias) causes a consistent, directional deviation of all results from the true value.

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