The Relationship of Quality Improvement and Quality Control

It is important to distinguish Juran’s conception of Quality Control as an integral component of

everyday work and management from the common misperception that QC is the same as quality

assurance or inspection. It’s well worth consulting Juran’s Quality Handbook1 on this point:

“Quality control and quality assurance have much in common. Each evaluates

performance. Each compares performance to goals. Each acts on the difference. However

they also differ from each other. Quality control has as its primary purpose to maintain

control. Performance is evaluated during operations, and performance is compared to

goals during operations. The resulting information is received and used by the operating

forces. Quality assurance’s main purpose is to verify that control is being maintained.

Performance is evaluated after operations, and the resulting information is provided to

both the operating forces and others who have a need to know.”

Accreditation is one particular form of quality assurance in health care and is performed by

external regulators or standards bodies. While important, quality assurance and accreditation are

not the focus of this white paper. Similarly, Quality Control should not be confused with the form

of “control” exercised by some managers who periodically respond to summary reports with

directives for staff to respond to problems that may not be current, or for which the manager lacks

complete information. A variant is “tampering” — making changes to a process, based on a limited

understanding of the principles of common cause and special cause variation.