Editing Software bug (section)

=== Cost ===

In 1994, NASA's [[Goddard Space Flight Center]] managed to reduce their average number of errors from 4.5 per 1,000 lines of code ([[Source lines of code|SLOC]]) down to 1 per 1000 SLOC.<ref name=NASA1994>{{cite journal
|journal=Software Engineering Laboratory Series
|title=An Overview of the Software Engineering Laboratory
|date=December 1994
|issue=SEL-94-005
|url=https://ntrs.nasa.gov/api/citations/19950022293/downloads/19950022293.pdf}}</ref>

Another study in 1990 reported that exceptionally good software development processes can achieve deployment failure rates as low as 0.1 per 1000 SLOC.<ref name="CobbMills1990">{{Cite journal |title=Engineering software under statistical quality control |journal=[[IEEE Software]] |url=https://trace.tennessee.edu/utk_harlan/14/|via=University of Tennessee – Harlan D. Mills Collection |last1=Cobb |first1=Richard H. |issue=6 |volume=7 |last2=Mills |first2=Harlan D. |doi=10.1109/52.60601 |year=1990 |page=46 |s2cid=538311 |language=en |issn=1937-4194 |author-link2=Harlan Mills}}</ref> This figure is iterated in literature such as ''[[Code Complete]]'' by [[Steve McConnell]],<ref name="McConnel1993">{{Cite book |title=Code Complete |last=McConnell |first=Steven C. |publisher=Microsoft Press |year=1993 |isbn=978-1556154843 |location=Redmond, Washington|page=611 |language=en |url=https://archive.org/details/codecompleteprac0000mcco/page/611/mode/1up?q=%22space+shuttle%22|via=archive.org |quote=(Cobb and Mills 1990) |author-link=Steve McConnell |url-access=registration}}</ref> and the ''NASA study on Flight Software Complexity''.<ref>{{cite journal
|author=Gerard Holzmann
|title=Appendix D – Software Complexity
|journal= Final Report: NASA Study on Flight Software Complexity (Daniel L. Dvorak (Ed.))
|date=March 5, 2009
|series=NASA Office of Chief Engineer Technical Excellence Program
|url= https://www.nasa.gov/wp-content/uploads/2015/04/418878main_fswc_final_report.pdf
}}</ref> Some projects even attained zero defects: the [[firmware]] in the [[IBM Wheelwriter]] typewriter which consists of 63,000 SLOC, and the [[Space Shuttle]] software with 500,000 SLOC.<ref name="CobbMills1990" />