Quality Control (QC) is a system of routine technical activities, to measure and control the quality of data – its collection and analysis, which results from the conduct of a protocol.
A QC system is designed to:
- provide routine and consistent checks to ensure data integrity, correctness, and completeness;
- identify and address errors and omissions; and
- document and archive inventory material.
Quality assurance (QA) can be defined as the guarantee from a review team that the entire study was adequately and correctly conducted and recorded according to the study protocol. Reviews, preferably by independent third parties, should be performed upon a finalised program of assessment and/or monitoring following the implementation of QC procedures.
A QA/QC Plan is designed to meet the following objectives:
- outline the procedures the program will use to ensure that data collection, analysis, storage, and management are of high quality;
- provide a means by which the quality of information produced can be maintained throughout the project, and
- provide a sound basis for documenting, evaluating and verifying the accuracy of results of project activities.
The QA objectives for collection and measurement of data include:
- Representativeness: The extent to which measurements actually depict the true environmental condition or population being evaluated;
- Completeness: A measure of the number of samples you must take to be able to use the information, as compared to the number of samples you originally planned to take;
- Precision: The degree of agreement among repeated measurements of the same characteristic on the same sample or on separate samples collected as close as possible in time and place; and
- Accuracy: The measure of confidence in a measurement. The smaller the difference between the measurement of a parameter and its “true” or expected value.