Quality control may be accomplished both internally and externally.
Internal quality control usually involves testing commercially purchased materials and comparing the results to known values.
- Since there is little delay in feedback, internal quality control is used for immediate decisions.
- Although internal quality control finds both random and systematic errors, it is subject to flaws in the testing process.
- If there was a systematic error present when a test's in-house baseline was set, further systematic error would go undetected.
