Quality Assurance in testing is the management process that makes sure you are doing the right things, the right way, all of the time. It includes documentation of the methods and standard operating procedures.

Quality Control in analytical science is checking that the results you have obtained are distributed normally within expectations. It includes adherence to the QA procedures to ensure that a product or process is acceptable or under control. The QC process may encompass the use of Control Charts or Westgard Rules.

Samples intended for internal laboratory quality control, without formally assigned property values or uncertainties (see ISO Guide 80). Sufficiently homogeneous and stable with one or more property value that can be used for maintaining or monitoring measurement processes. Known colloquially in some jurisdictions as IRM's (Internal Reference Materials).