The Cove Business Standards Discussion Forums More Free Files Forum Discussion Thread Post Attachments Listing Cove Discussion Forums Main Page
UL - Underwriters Laboratories - Health Sciences
Go Back   The Elsmar Cove Business Systems and Standards Discussion Forums > Common Quality Assurance Processes and Tools > Statistical Analysis Tools, Techniques and SPC
Forum Username

Elsmar Cove Forum Visitor Notice(s)

Wooden Line

What are Difference Charts and How do you construct Difference Charts?


Elsmar XML RSS Feed
Elsmar Cove Forum RSS Feed

Monitor the Elsmar Forum
Sponsor Links




Courtesy Quick Links


Links that Cove visitors will find useful in your quest for knowledge:

International Standards Bodies - World Wide Standards Bodies

ASQ - American Society for Quality

International Standards Organization - ISO Standards and Information

Howard's
International Quality Services


Marcelo Antunes'
SQR Consulting, and
Medical Devices Expert Forum


Bob Doering
Bob Doering's Blogs and,
Correct SPC - Precision Machining


Ajit Basrur
Claritas Consulting, LLC


NIST's Engineering Statistics Handbook

IRCA - International Register of Certified Auditors

SAE - Society of Automotive Engineers

Quality Digest

IEST - Institute of Environmental Sciences and Technology

Reply
 
Thread Tools Search this Thread Rate Thread Content Display Modes
  Post Number #1  
Old 21st April 2009, 06:27 AM
sathis's Avatar
sathis

 
 
Total Posts: 107
Question What are Difference Charts and How do you construct Difference Charts?

Any Details of "Difference Charts"?

How to construct "Difference Charts"?


Sathis

Sponsored Links
  Post Number #2  
Old 21st April 2009, 06:52 AM
Miner's Avatar
Miner

 
 
Total Posts: 4,007
Re: What is Difference Charts?

I did not recognize it by this name, but Google shows that it is a type of Short Run SPC where the difference between the sample measurement and a target value is plotted on the control chart.

For example, you have a length cut-off process that consists of a lot of short production runs at hundreds of different target lengths. The variation is the same regardless of the target setting. The center line of the X-bar or X chart is zero. The R-bar or MR-bar is calculated the standard way. The control limits are calculated using the standard method (using R-bar or MR-bar), but are applied about the zero target line.
Thanks to Miner for your informative Post and/or Attachment!
Sponsored Links

  Post Number #3  
Old 21st April 2009, 10:03 AM
Darius's Avatar
Darius

 
 
Total Posts: 551
Re: What are Difference Charts and How do you construct Difference Charts?

Yes indeed, it is some kind of Short Run SPC chart.

The idea behind this is to chart different products on the same chart even tho have different target.

There are different versions of this kind of chart.
* the difference chart abs(Value-Target_prod)
* the Z chart (or Zed not sure), the you chart all products at once no matter they have different target and variation. The ones that you plot (Value-Target_prod)/Stdev_prod on the same chart


Search for SQCpack. Extracted from their manual, it's not advertizing, just their manual looks OK

Quote:
In Short-run SPC, special control charts allow you to chart differences from a target value. Sometimes the absolute difference from target is plotted. In other cases, a normalized difference from target is plotted.
The idea is that a zero difference from target is good and any deviation away from zero is bad.
......
A Difference chart is plotting the difference from target in absolute units. A Zed chart takes the difference from target, normalizes this difference in units of sigma, and plots this normalized value as the difference.
Thank You to Darius for your informative Post and/or Attachment!
  Post Number #4  
Old 28th April 2009, 11:09 AM
pagnonig's Avatar
pagnonig

 
 
Total Posts: 79
Re: What are Difference Charts and How do you construct Difference Charts?

The attachments may help you.
Giuseppe
Attached Files: 1. Scan for viruses before using, 2. Please report any 'bad' files by Reporting this post, 3. Use at your Own Risk.
File Type: pdf (Article).Wh_difference charts compensate for moving targets.pdf (188.0 KB, 582 views)
File Type: pdf (Article).Wh_Zed charts compares oranges and apples.pdf (144.1 KB, 383 views)
Thanks to pagnonig for your informative Post and/or Attachment!
Reply

Lower Navigation Bar
Go Back   The Elsmar Cove Business Systems and Standards Discussion Forums > Common Quality Assurance Processes and Tools > Statistical Analysis Tools, Techniques and SPC

Bookmarks



Visitors Currently Viewing this Thread: 1 (0 Registered Visitors (Members) and 1 Unregistered Guest Visitors)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Forum Search
Display Modes Rate Thread Content
Rate Thread Content:

Forum Posting Settings
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Emoticons are On
[IMG] code is On
HTML code is Off


Similar Discussion Threads
Discussion Thread Title Thread Starter Forum Replies Last Post or Poll Vote
What is the difference between X Bar - R Charts and Average Chart? Muhd Firdaus Statistical Analysis Tools, Techniques and SPC 7 22nd November 2013 09:56 PM
Dr. Wheeler article: What About p-Charts? - When should we use the specialty charts bobdoering Statistical Analysis Tools, Techniques and SPC 2 4th October 2011 12:00 PM
Does anyone use Median Charts instead of Xbar & R charts? Leonardo Lopez Statistical Analysis Tools, Techniques and SPC 3 26th May 2004 02:31 PM
High Cpk's and Control Charts - Is it justified to stop using control charts? MSAFAI Capability, Accuracy and Stability - Processes, Machines, etc. 7 11th August 2001 01:23 PM



The time now is 04:00 PM. All times are GMT -4.
Your time zone can be changed in your UserCP --> Options.


 
 


NOTE: This forum uses "Cookies" - A Peachfarm Internet Property