Quality Assurance and Quality Control

Quality assurance

It refers to a process in which a lab ensures quality results by closely monitoring preanalytical, analytical, and postanalytical stages of testing.

Quality control

It is part of the analytical phase of quality assurance and is a process of monitoring results from control samples to verify accuracy of patient results

Standard deviation

It is the most frequently used measure of variation

Coefficient of variation (CV)

Index of precision used to compare the dispersion of two or more groups of data with different units / concentrations.

T-test

It is used to determine if there is a significant difference between the means of two groups of data

F-test

It is used to determine if there is a significant difference between the SD of two groups of data

Verify that a lab procedure is performing correctly

Quality control samples are assayed on a regular schedule in order to:

20 days

A new instrument or a new lot of reagents should be analyzed for how many days of quality control?

Shewart plot

The Levey-Jennings chart is also called a:

Levey-Jennings chart

It is the most common presentation for evaluating QC results

Trend

Control values are increasing or decreasing for six consecutive runs. What type of LJ chart error is this?

Shift

There are six consecutive control values on the same side of the mean. What type of LJ chart error is this?

Outliers

There are highly deviating values and the control result is outside established limits. What type of LJ chart error is this?

• 1(3S)

• R4s

Which Westgard rules are examples of RANDOM errors?

• 2(2S)

• 4(1S)

• 10x

Which Westgard rules are examples of SYSTEMATIC errors?

Random error

Which type of error is present in all measurements and doesn’t recur in a regular pattern?

Systematic error

Which type of error influences ALL observations consistently in one direction?

• Error due to dirty glassware

• Use of wrong pipet

• Voltage fluctuation

• Sampling error

• Anticoagulant or drug interference

Examples of random errors

• Dirty photometer

• Faulty ISE

• Evaporation or contamination of standards or reagents

Examples of systematic errors

Proficiency testing

It is also known as external quality assessment

Delta check

It is a process that compares a patient's current data with their previous results.