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 > Inspection, Prints (Drawings), Testing, Sampling and Related Topics
Forum Username

Elsmar Cove Forum Visitor Notice(s)

Wooden Line

Determining Sample Size for Attribute Data


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

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 30th June 2006, 07:33 AM
nwillnow

 
 
Total Posts: 7
Please Help! Determining Sample Size for Attribute Data

Hey everyone. I'm currently trying to prove that a system I have in place is reliable to the severity level required and I'm in need of sampling plan information. I have a standard operation procedure which tells me that for 95% confidence and 95% reliability (1.0 AQL) that I need 59 samples for c=0, and 95 for c=1, but no information for c=2,3,4,...

All it tells me about the plan is that "The attribute data sample
sizes are based on the binomial distribution for the corresponding reliability and confidence level requirements." I've tried using Statgraphics and MiniTab to help calculate what the c=2 sample would be, but I can't figure out how.

Is this a common standard I'm looking at? My problem is that I'm working backwards. I'm trying to use pass/fail data I have collected over a number of weeks to show that the number of failures I'm seeing per week is acceptable, as opposed to structuring a validation around a sample size to test.

I've looked at the ANSI/ASQC Z1.4 standard, but that seems entirely different. Any suggestions?

Sponsored Links
  Post Number #2  
Old 30th June 2006, 08:15 AM
Michael Walmsley

 
 
Total Posts: 157
Re: Determining Sample Size for Attribute Data

What you have referenced comes from the Bayes Success-Run Theorem.
for c = 1 thru 10 reference the following (the theoretical aspects can be found on the attached link.

Rel 0.95
Conf 0.95
# Fail allowed "c" 0 1 2 3 4 5
n = 58.4 93 124 153 180.4 207.4

# Fail allowed "c" 6 7 8 9 10
n = 234 260 285.4 311 336

http://www.weibull.com/LifeDataWeb/d...est_design.htm
Sponsored Links

  Post Number #3  
Old 30th June 2006, 08:56 AM
Tim Folkerts's Avatar
Tim Folkerts

 
 
Total Posts: 972
Re: Determining Sample Size for Attribute Data

A while back I posted a spreadsheet for calculating sampling plans and it can determine the numbers you are looking for:
Sampling Spreadsheet to help determine the sample size for sampling plans

For 95% reliability, enter 5% in the "Unacceptable Quality Level" cell
For 95% certainty, enter 5% in the "Beta Risk" cell

Then adjust the sample size cell (or the slider) and watch the "RE" cell (the reject number). Once it changes, then you have the smallest sample needed to acheive your goals. Keep increasing the sample size and you will reach Re=1, Re=2, ... I checked a few and they agree with the numbers posted already.

Obviously, you could change the "Unacceptable Quality Level" and the "Beta Risk" for other levels. You can also "reverse engineer" the formulas to see how I got the results.


Tim
  Post Number #4  
Old 30th June 2006, 10:26 AM
nwillnow

 
 
Total Posts: 7
Re: Determining Sample Size for Attribute Data

Sound. Cheers for that lads! Never would have found that on me own.
Reply

Lower Navigation Bar
Go Back   The Elsmar Cove Business Systems and Standards Discussion Forums > Common Quality Assurance Processes and Tools > Inspection, Prints (Drawings), Testing, Sampling and Related Topics

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
Smilies 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
Bayes Success-Run on Attribute Data - Determining Sample Size blazin912 Statistical Analysis Tools, Techniques and SPC 2 2nd June 2014 12:06 PM
Sample Size for Attribute Binary Data optomist1 Inspection, Prints (Drawings), Testing, Sampling and Related Topics 10 3rd December 2012 04:15 PM
Sample Size for Attribute Data - Large Production Lots vitaudi Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2 15th September 2011 04:30 AM
Sampling Plan problem - Determining Sample Size for both Attribute and Variables Data woonsiong ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2 19th April 2011 09:34 PM
Finding Sample Size - Data Type is Attribute Nissim Shaked Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7 19th September 2006 02:17 AM



The time now is 06:26 PM. All times are GMT -4.
Your time zone can be changed in your UserCP --> Options.


 
 


NOTE: This forum uses "Cookies"