Hello ,
I was just curious of the SPC terminologies definition and evolvement over years.Can anybody throw some light on this.I know it would be like writing another book, but something short and sweet, like when and why the concept of CPk and PPk came in and what they actually mean. :thanx:

Welcome qualithirsty!

Great question and I don't know. I'm sure a better informed statistical type will be along soon and I look for their input. Atul????????

Al...

hmmmm.. this is MY first post so.......

Try this link, it covers Cpk and Ppk pretty well....

http://www.qualityadvisor.com/library/capability/Is_Cpk_the_best_capability_index.htm

Your question is very broad but I believe there are some possibilities for where quality terms and acronyms came into being. In the research that I have done on the history of quality terms usually leads to the following:

1. The U.S. military and other government agencies.
2. National or International Standards organizations.
3. The Academia from Colleges and Universities.
4. Large corporations from around the world.

The military and government like to use acronyms, do a good job of documenting and teaching them and make them readily available to the public. Japanese companies have also initiated new terminology.

ASQ has a Journal of Quality Technology where new terms are first used and I am sure there are other quality and statistics journals that can be researched for information. There is a large body of literature on quality and its history plus there are many sites on the Internet. The problem you may have is finding confirmation of where it started since there are multiple claims to some quality terms or you will only find references of when it was first published not necessarily used.

Bill Pflanz

Welcome Qualithirsty and Erich! :bigwave:
Great question and I don't know. I'm sure a better informed statistical type will be along soon and I look for their input. Atul????????
Frankly, I don't know too. Never had the opportunity to research in that direction. As Bill said, this is a long history and we will have to begin our search from 1920's or so! It would be interesting to trace the history from control charts and Cpks to the present day 6Sigma jargon.

Hello ,
I was just curious of the SPC terminologies definition and evolvement over years.Can anybody throw some light on this.I know it would be like writing another book, but something short and sweet, like when and why the concept of CPk and PPk came in and what they actually mean. http://elsmar.com/Forums/images/smilies/thank_you.gif
As others have pointed out, it's a very broad question. The best place to research such things is a university library. There's also Google Scholar (http://scholar.google.com/), a subset of Google that allows keyword searches of scholarly literature.

There have also been some discussions on the subject here. Do a search of the terms you are interested in. Regarding Cpk and Ppk origins and definitions, I added these thoughts some time ago:

http://elsmar.com/Forums/showpost.php?p=64107&postcount=13

http://elsmar.com/Forums/showpost.php?p=60861&postcount=5

hmmmm.. this is MY first post so.......

Try this link, it covers Cpk and Ppk pretty well....

http://www.qualityadvisor.com/library/capability/Is_Cpk_the_best_capability_index.htm

Thanks Erich, :)

Seems to be a good site, added to favourites.
:thanx:

There have also been some discussions on the subject here. Do a search of the terms you are interested in. Regarding Cpk and Ppk origins and definitions, I added these thoughts some time ago:

http://elsmar.com/Forums/showpost.php?p=64107&postcount=13

http://elsmar.com/Forums/showpost.php?p=60861&postcount=5

Thanx Rob, :D

I was browsing a manufacturers own SPC study sheet , he had just subtracted 0.5 from a CPk value and had named it as long term process capability.Is this a thumb rule or any history behind this.

:confused: