The Cove Business Standards Discussion Forums
Go Back   The Elsmar Cove Business Systems and Standards Discussion Forums > >
Forum Username

Elsmar Cove Forum Visitor Notice(s)

Wooden Line

Design Verification Sample Size - What philosophies are out there

Monitor the Elsmar Forum
Courtesy Quick Links


Links Elsmar Cove visitors will find useful in the quest for knowledge and support:

Jennifer Kirley's
Conway Business Services


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



International Standards Bodies - World Wide Standards Bodies

AIAG - Automotive Industry Action Group

ASQ - American Society for Quality

International Organization for Standardization - ISO Standards and Information

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


Some Related Topic Tags
design and development, design verification, sample size
Reply
 
Thread Tools Search this Thread Rate Thread Content Display Modes
  Post Number #1  
Old 27th March 2006, 03:12 PM
MNPIKE

 
 
Total Posts: n/a
Question Design Verification Sample Size - What philosophies are out there

All -

Recently we have done device design verification testing on sample size of 3. Recently to achieve a 90/90 (passing rate/confidence level), that has been increased to a much larger number. To my knowledge the 90/90 is more of a manufacturing tool, not design. UL for example only requires a "representative sample size of one". I am curious what philosophies are out there on verification sample size and how those were determined as well as any other knowledge out there on this topic.

Thanks!

Sponsored Links
  Post Number #2  
Old 27th March 2006, 03:44 PM
Jim Wynne's Avatar
Jim Wynne

 
 
Total Posts: 14,228
Quote:
In Reply to Parent Post by MNPIKE

All -

Recently we have done device design verification testing on sample size of 3. Recently to achieve a 90/90 (passing rate/confidence level), that has been increased to a much larger number. To my knowledge the 90/90 is more of a manufacturing tool, not design. UL for example only requires a "representative sample size of one". I am curious what philosophies are out there on verification sample size and how those were determined as well as any other knowledge out there on this topic.

Thanks!
Welcome to the Cove, MNPIKE

It might be good to provide a little more information, starting with defining terms. What do you mean by "design verification"? Under what circumstances are the individuals being built? Are they design prototypes, or assemblies made using the same materials, processes and machines intended for use in regular production?

The quote from UL looks like one of those Wheel of Fortune "Before and After" puzzles; it might be "representative sample size," or "sample size of 1," but strung together it doesn't make sense.
  Post Number #3  
Old 27th March 2006, 04:02 PM
MNPIKE

 
 
Total Posts: n/a
During design verification we are testing to requirements. Thus the output is either pass or fail. The devices used in these tests are representative of production devices. "Tests are made on one representative sample of the item being tested.", is the entire string from UL 60601-1.

Testing 90/90 to me makes sense if one were verifying production but not design. I was curious what others are doing.

Thanks for the help!
  Post Number #4  
Old 14th February 2013, 12:55 PM
MEANMC

 
 
Total Posts: 3
Re: Design Verification Sample Size - What philosophies are out there

I work with medical devices, but I do use LTPD for design verification also.
We use LTPD to allow us make confidence and reliability statements such as 95/95 or 95/99.
Thanks to MEANMC for your informative Post and/or Attachment!
  Post Number #5  
Old 16th February 2013, 09:32 AM
sagai

 
 
Total Posts: 1,133
Re: Design Verification Sample Size - What philosophies are out there

Hello there,
I have just faced with this sampling kind of questions and the reference I have found useful was the standard called ISO2859.
There is a legacy copy available over the internet here, may be helpful.

I am also still a bit struggling how to accommodate such statistical method to areas are not directly relate to incoming and outgoing real product inspections and I am not certain if this level of scrutiny really count or not.

Meanmc, can you give a little bit insight about the method you apply to encapsulate this statistical sampling into design verification acivities? ... of course on the level of detail we can know more about.

Cheers!
  Post Number #6  
Old 16th February 2013, 12:12 PM
MEANMC

 
 
Total Posts: 3
Re: Design Verification Sample Size - What philosophies are out there

For areas of our quality management system that require lot to lot control like incoming inspection I use AQL.
As Design Verification is concerned with verifying the design ( I.e. lot to lot variation is not a focus). Then tools like LTPD or MTBF are appropriate. MTBF is useful for machines etc. I use LTPD especially where the device is single use and the test is destructive. Using LTPD allows you make certain confidence and reliability statements in relation to the design.
I have successfully used these plans on numerous FDA and European medical device submissions.
Obviously using variable data helps offer opportunities in relation to smaller sample sizes.
Thanks to MEANMC for your informative Post and/or Attachment!
Reply

Lower Navigation Bar
Go Back   The Elsmar Cove Business Systems and Standards Discussion Forums > >

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
Design Verification: "Difference" in Sample Size Calculations? mtwalenciak Design and Development of Products and Processes 1 18th January 2014 08:24 AM
Determining Sample Size for Design Verification and Design Validation edisoar Other Medical Device and Orthopedic Related Topics 20 3rd December 2012 07:32 PM
Sample Size for Design Verification and Validation gxzn008 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 6 9th November 2011 09:17 AM
Sample Size for Design Verification (Prototype Testing) for Medical Devices amadeuscurse Qualification and Validation (including 21 CFR Part 11) 12 27th July 2011 04:56 AM
Sample Size in Design Verification & Process Validation MasterBB Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2 16th November 2009 09:00 PM



The time now is 08:15 PM. All times are GMT -4.
Your time zone can be changed in your UserCP --> Options.



Misc. Internal Links


NOTE: This forum uses "Cookies"