The Elsmar Cove Forum DPMO (defects per million opportunities) - Key word being OPPORTUNITIES
 Forum User Name Keep Me Logged In Password
 Register Photo Albums Blogs FAQ Registered Visitors Social Groups Calendar Search Today's Posts Mark Forums Read

 Elsmar Cove Forum Visitor Notice(s) It is the Labor Day holiday weekend in the US so activity in the forum will be slow for a few days. Normal activity in the forum will start to pick up again mid-week. Please see the forum Calendar for more information on the holiday.Logged In Registered Members can click the red X to close this notice box.

 Search the Elsmar Cove @import url(http://www.google.com/cse/api/branding.css); Custom Search Monitor the Elsmar Forum Monitor New Forum Posts Follow Marc & Elsmar Elsmar Cove Groups Sponsor Links Donate and \$ Contributor Forum Access Courtesy Quick Links Links that Elsmar Cove visitors will find useful in your quest for knowledge: Howard'sInternational Quality Services Marcelo Antunes'SQR Consulting Bob Doering'sCorrect SPC - Precision Machining NIST's Engineering Statistics Handbook IRCA - International Register of Certified Auditors SAE - Society of Automotive Engineers Quality Digest Portal IEST - Institute of Environmental Sciences and Technology ASQ - American Society for Quality

#1
16th November 2008, 05:55 PM
 tww11 Inactive Registered Visitor   Registration Date: Mar 2007 Posts: 7 Thanks Given to Others: 8 Thanked 0 Times in 0 Posts Karma Power: 31 Karma: 10
DPMO (defects per million opportunities) - Key word being OPPORTUNITIES

I keep getting conflicting information on DPMO. The key word being OPPORTUNITIES. I think people are confusing DPMO and PPM. Some people think it tells them how many parts out of 1million have defects, but we are not measuring parts defective in DPMO. Does the 1,000,000 in PPM mean 1 million parts and the 1,000,000 im DPMO means 1 million opportunites?

Here is my interpretation:

1000 units, 5 defects, 2 opportunites for defects per unit

1000 units X 2 opps per unit= 2000 total opportunities

5 defects / 2000 total opportunities= .0025

So, every opportunity shares .0025 of a defect.

Now, I take .0025 X 1,000,000 opportunites (not parts)= 2500 defects per million opportunites

This tells me nothing about the amount of parts that have defects. That is what PPM is for. This only tells me how many defects I will have over 1million opportunities. Is this right?

#2
16th November 2008, 06:34 PM
 Desara01 Inactive Registered Visitor   Registration Date: Nov 2008 Location: Connecticut Posts: 76 Thanks Given to Others: 31 Thanked 16 Times in 11 Posts Karma Power: 31 Karma: 295
Re: Dpmo help!!

Hi tww - hope you're well this evening. What a great question! And you are, in fact correct. Good for you to question the numbers!

DPMO allows us to examine each unit and determine how many possible ways it can fail. PPM looks at a P/F for each part. They will be the same number if you consider the number of opportunities for failure to be - you guessed it - 1. Here's an example. A company is counting inventory. They scan in barcodes - either the scan works or it doesn't. Now, the numbers are one and the same. If, however, I were scanning for 6 pieces of information, now the numbers are considerable different, yes?

Both numbers can/should be important in most situations - management needs to know the acceptable "pass" rate - that's ppm, right? But DPMO might tell a very different story. If there are 5 opps to fail, and I'm failing 4/5 most of the time - well that's obviously more severe - or requires a different attack plan - vs. if I'm failing on one recurring characteristc, right?

When you calculate DPMO, just make sure you are very clear on what the "opportunities for failure" are, get agreement from management, and remain consistent as you track your improvement efforts.

One more thought/observation: I have seen DPMO manipulated by management to make the number look better by not counting all the opportunities. I've also seen the number manipulated by Quality Managers in the other direction.

Key point: create a clear operational definition of the metric and ensure it's communicated and understood. Then you can start to make good decision. Dr. Deming said something like this - Data only has meaning when we know how it was counted/collected. Or something to that effect. If you want more info on operational definitions, let me know.

Hopes this helps. Cheers!
 Thank You to Desara01 for your informative Post and/or Attachment!
#3
16th November 2008, 06:40 PM
 Miner Forum Moderator   Registration Date: Apr 2002 Location: Greater Milwaukee area, Wisconsin Posts: 3,507 Thanks Given to Others: 603 Thanked 2,044 Times in 1,300 Posts Blog Entries: 16 Karma Power: 438 Karma: 18664
Re: Dpmo help!!

Excellent response by Desara01. The key take-away is the need for an operational definition for "Opportunity". Keep it as simple as possible, such as part count for circuit boards.

__________________

"A fool can learn from his own experiences; the wise learn from the experience of others." - Democritus, 460-370 B.C.
#4
16th November 2008, 06:55 PM
 Stijloor Super Moderator   Registration Date: May 2003 Location: Charlotte, North Carolina. Posts: 14,526 Thanks Given to Others: 3,192 Thanked 4,527 Times in 3,207 Posts Karma Power: 1548 Karma: 25248
Re: Dpmo help!!

Quote:
 In Reply to Parent Post by Desara01 Dr. Deming said something like this - Data only has meaning when we know how it was counted/collected. Or something to that effect.
Dr. Deming quote:

Quote:
 When information is obtained, or data is measured, the method, or process used to gather information, greatly affects the results.
Thank you for mentioning the concept of "operational definition" in your post!

Stijloor.
#5
16th November 2008, 07:03 PM
 Desara01 Inactive Registered Visitor   Registration Date: Nov 2008 Location: Connecticut Posts: 76 Thanks Given to Others: 31 Thanked 16 Times in 11 Posts Karma Power: 31 Karma: 295
Re: Dpmo help!!

thank you stil for the quote - I was in the ballpark, anyway :-)
#6
16th November 2008, 07:26 PM
 Stijloor Super Moderator   Registration Date: May 2003 Location: Charlotte, North Carolina. Posts: 14,526 Thanks Given to Others: 3,192 Thanked 4,527 Times in 3,207 Posts Karma Power: 1548 Karma: 25248
Re: Dpmo help!!

Quote:
 In Reply to Parent Post by Desara01 thank you stil for the quote - I was in the ballpark, anyway :-)
Yes you were! Yes, Dr. Deming...what a legacy and wisdom he left... His lessons are as fresh and are as current today as they were when he started his long and impressive career. I still refer to "Out of the Crisis" and "The New Economics" and continue to gain valuable insights.

Learning never ends.

Stijloor.
#7
16th November 2008, 10:48 PM
 tww11 Inactive Registered Visitor   Registration Date: Mar 2007 Posts: 7 Thanks Given to Others: 8 Thanked 0 Times in 0 Posts Karma Power: 31 Karma: 10
Re: DPMO (defects per million opportunities) - Key word being OPPORTUNITIES

I'm doing very well. Thank you. I hope you are too.

Thank you very much for the answers. The more I learn about Six Sigma, the more I realize that alot of people don't know what they are doing. It was frustrating me because alot of people mixed PPM and DPMO together or think its the same metric. Maybe when the opportunity is 1 like you said.

Well, I'm taking a study course and it states "As a yield measurement, DPMO indicates the number of defects in a process observed during a production of one million units."

This is the statement that got me confused. They say units, but they have to mean opportunities right? Otherwise they would be comparing apples to oranges. If you multiply the average defect per opportunity by 1 million parts, how would that tell you how many defects per opportunity I have?
#8
16th November 2008, 10:52 PM
 tww11 Inactive Registered Visitor   Registration Date: Mar 2007 Posts: 7 Thanks Given to Others: 8 Thanked 0 Times in 0 Posts Karma Power: 31 Karma: 10
Re: DPMO (defects per million opportunities) - Key word being OPPORTUNITIES

Here's another example of why people are confused. This is something I found online. Read the last sentence below. Why would they say this when it's not the same metric?

2. Defects per Million Opportunities, or DPMO � indicates how many defects would arise if there were one million opportunities. In manufacturing, DPMO is often called PPM (parts per million).

 The Elsmar Cove Forum DPMO (defects per million opportunities) - Key word being OPPORTUNITIES

 Bookmarks

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

 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 Forum Rules

 Similar Discussion Threads Discussion Thread Title Thread Starter Forum Replies Last Post or Poll Vote jackylpt Definitions, Acronyms, Abbreviations and Interpretations 7 24th March 2011 06:16 PM optomist1 Capability, Accuracy and Stability - Process, Machine, etc. 4 4th March 2011 03:47 PM Sushil Six Sigma 7 25th July 2008 02:09 PM Marc Definitions, Acronyms, Abbreviations and Interpretations 1 5th May 2006 09:56 AM faujix Statistical Analysis Tools, Techniques and SPC 5 6th December 2001 01:56 AM

The time now is 07:24 PM. All times are GMT -4.