ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

Effective Date: 2014 Version #1

Chapter 5

Procedure Name: Quality Control

Purpose and Principle The term “quality control” can be defined as the process of monitoring the precision and accuracy of a test proce- dure. The term “quality management system” not only encompasses quality control, but includes many other activi- ties, such as: maintaining and calibrating equipment, training personnel and continued competency assessment, reporting results, and record keeping (1, 2). The purpose of this procedure is to describe the framework for quality control activities needed to ensure that measurements are being made within acceptable limits of accuracy and precision. Specific quality control proce- dures for the various tests used by the PF laboratory are described in the technical procedure chapters.

Terms and Definitions

Accuracy Precision

How well the measurement reflects the true or correct value

Measurement variability (repeatability) and is completely independent of accuracy or truth. Errors that occur without prediction or regularity, tend to decrease precision, and often result from inherent variation in the instrumentation Errors within the test system or methodology (e.g., instrument calibration or mal- function) that tend to produce bias The sum of observed values divided by the number of observations A measurement of variability or tendency of values to vary from the arithmetic mean. A mathematical expression of variability calculated by dividing the SD by the mean

Random errors

Systematic errors

Biologic control (standard) Healthy nonsmoking individual used in quality control Mean

Standard deviation (SD)

Coefficient of variation

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