Editing Quality control (section)

== History and introduction ==
{{See also|History of technology}}
Early [[stone tools]] such as [[anvil]]s had no holes and were not designed as [[interchangeable parts]]. [[Mass production]] established processes for the creation of parts and system with identical dimensions and design, but these processes are not uniform and hence some customers were unsatisfied with the result. Quality control separates the act of [[test method|testing]] [[product (business)|product]]s to uncover defects from the decision to allow or deny product release, which may be determined by fiscal constraints.<ref name="Shewhart">{{cite book|last1=Shewhart|first1=Walter A. (Walter Andrew)|last2=Deming|first2=W. Edwards (William Edwards)|title=Statistical method from the viewpoint of quality control|date=1939|publisher=The Graduate School, The Department of Agriculture|location=Washington|pages=1–5|url=https://archive.org/stream/CAT10502416#page/2/mode/2up}}</ref> For contract work, particularly work awarded by government agencies, quality control issues are among the top reasons for not renewing a contract.<ref>{{cite web |url=http://www.opm.gov/fedclass/gs1910.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.opm.gov/fedclass/gs1910.pdf |archive-date=2022-10-09 |url-status=live |title=Position Classification Standard for Quality Assurance Series, GS-1910 |date=March 1983 |publisher=US Office of Personnel Management |access-date=21 December 2012 }}</ref>

The simplest form of quality control was a sketch of the desired item. If the sketch did not match the item, it was rejected, in a simple [[Go/no go]] procedure. However, manufacturers soon found it was difficult and costly to make parts be exactly like their depiction; hence around 1840 tolerance limits were introduced, wherein a design would function if its parts were measured to be within the limits. Quality was thus precisely defined using devices such as [[plug gauge]]s and [[ring gauge]]s. However, this did not address the problem of defective items; recycling or disposing of the [[waste]] adds to the cost of production, as does trying to reduce the defect rate. Various methods have been proposed to prioritize quality control issues and determine whether to leave them unaddressed or use [[quality assurance]] techniques to improve and stabilize production.<ref name="Shewhart" />