Talk:Levey–Jennings chart

Try searching under "Levy-Jennings". The proper spelling does not have the extra "e".
 * Actually, it DOES. It is used and written with an extra 'e' at our lab and in our literature (US and UK), though. Dr. F.C. Turner - [ USERPAGE | USERTALK ] - 13:12, 15 February 2010 (UTC)

removed comment
removed from article " Correction: The Levey-Jennings chart is NOT the same as the Shewhart Individuals chart. The Levey-Jennings chart uses the long-term (i.e., population) estimate of sigma whereas the Shewhart chart uses the short-term (i.e., within the rational subgroup) estimate. Dr. John Flaig". I slightly changed what was said in response, but something better is needed. Melcombe (talk) 13:32, 30 November 2009 (UTC)

Malcombe,

Changing the text to say they are "similar" helps a little, but leaves open the question of just how they are similar. I think it is better to say exactly how they differ as this leaves no confusion. Therefore, I would remove the current comment and replace it with:

The Levey-Jennings chart differs from the Shewhart Individuals control chart in the way sigma is estimated. The Levey-Jennings chart uses the long-term (i.e., population) estimate of sigma whereas the Shewhart chart uses the short-term (i.e., within the rational subgroup) estimate.

John 72.153.169.233 (talk) 21:41, 30 November 2009 (UTC)


 * I have copied this in, with minor changes. I am not sure that "rational subgroup" has an obvious meaning here. Do make your own changes to the article, but not marked as "correction" as before ...just as part of the article. Melcombe (talk) 10:38, 2 December 2009 (UTC)