Span Process Capability

This topic has 2 replies, 3 voices, and was last updated 19 years, 10 months ago by Carl H.

Viewing 3 posts - 1 through 3 (of 3 total)

Author

Posts
August 30, 2002 at 1:36 pm #30230

Brian Kluchnick
★ 20 Years ★
Participant

@Brian-Kluchnick Include @Brian-Kluchnick in your post and this person will
be notified via email.

I am trying to establish process capablity for span data (29 thousand elements, ranging from -351 to 1400). My data is non-normal. Since I have negative values, I am unable to transform the data.
Does anyone now the best to deal with this type of situation and establish process capability?
Thanks.

0

August 30, 2002 at 1:42 pm #78527

Marc Richardson
★ 20 Years ★
Participant

@Marc-Richardson Include @Marc-Richardson in your post and this person will
be notified via email.

Why can’t you just add 351 to all the values first and then try to tranform them? If that won’t work. then use nonparametric methods.
Marc Richardson
Sr. Q.A. Engineer

0

August 30, 2002 at 7:34 pm #78539

Carl H
★ 20 Years ★
Participant

@Carl-H Include @Carl-H in your post and this person will
be notified via email.

1. I would add 352 (gets all values >0) to each value then do appropriate transformation to get it Normal.
2. Run a capability analysis anyhow. Read the obseved % or DPMO values out of spec limits. Get Z value(s) from Z table. Example. 2.0% out of spec high, 1.0% out of spec low. Z table gives Z = 1.88 at 3%.
3. Try a probablity plot (using software). Read off the observed % from this and look up Z again.
Carl

0
Author

Posts

Viewing 3 posts - 1 through 3 (of 3 total)

The forum ‘General’ is closed to new topics and replies.