Accendo Reliability

Your Reliability Engineering Professional Development Site

  • Home
  • About
    • Contributors
  • Reliability.fm
    • Speaking Of Reliability
    • Rooted in Reliability: The Plant Performance Podcast
    • Quality during Design
    • Critical Talks
    • Dare to Know
    • Maintenance Disrupted
    • The Leadership Connection
    • Practical Reliability Podcast
    • Reliability Matters
    • Reliability it Matters
    • Maintenance Mavericks Podcast
    • Women in Maintenance
    • Accendo Reliability Webinar Series
    • Asset Reliability @ Work
  • Articles
    • CRE Preparation Notes
    • on Leadership & Career
      • Advanced Engineering Culture
      • Engineering Leadership
      • Managing in the 2000s
      • Product Development and Process Improvement
    • on Maintenance Reliability
      • Aasan Asset Management
      • CMMS and Reliability
      • Conscious Asset
      • EAM & CMMS
      • Everyday RCM
      • History of Maintenance Management
      • Life Cycle Asset Management
      • Maintenance and Reliability
      • Maintenance Management
      • Plant Maintenance
      • Process Plant Reliability Engineering
      • ReliabilityXperience
      • RCM Blitz®
      • Rob’s Reliability Project
      • The Intelligent Transformer Blog
    • on Product Reliability
      • Accelerated Reliability
      • Achieving the Benefits of Reliability
      • Apex Ridge
      • Metals Engineering and Product Reliability
      • Musings on Reliability and Maintenance Topics
      • Reliability Engineering Insights
      • Reliability in Emerging Technology
    • on Risk & Safety
      • CERM® Risk Insights
      • Equipment Risk and Reliability in Downhole Applications
      • Operational Risk Process Safety
    • on Systems Thinking
      • Communicating with FINESSE
      • The RCA
    • on Tools & Techniques
      • Big Data & Analytics
      • Experimental Design for NPD
      • Innovative Thinking in Reliability and Durability
      • Inside and Beyond HALT
      • Inside FMEA
      • Integral Concepts
      • Learning from Failures
      • Progress in Field Reliability?
      • Reliability Engineering Using Python
      • Reliability Reflections
      • Testing 1 2 3
      • The Manufacturing Academy
  • eBooks
    • Reliability Engineering Management DRAFT
  • Resources
    • Accendo Authors
    • FMEA Resources
    • Feed Forward Publications
    • Openings
    • Books
    • Webinars
    • Journals
    • Higher Education
    • Podcasts
  • Groups
    • Reliability Integration
    • Mastermind
    • Study Groups
  • Courses
    • 14 Ways to Acquire Reliability Engineering Knowledge
    • Reliability Analysis Methods online course
    • Measurement System Assessment
    • SPC-Process Capability Course
    • Design of Experiments
    • Foundations of RCM Online Course
    • Reliability Engineering Statistics
    • An Introduction to Reliability Engineering
    • Process Capability Analysis course
    • Root Cause Analysis and the 8D Corrective Action Process course
    • Return on Investment online course
    • CRE Preparation Online Course
    • Quondam Courses
  • Webinars
    • Upcoming Live Events
  • Calendar
    • Call for Papers Listing
    • Upcoming Webinars
    • Webinar Calendar
  • Login
    • Member Home

Progress in Field Reliability?

by Larry George Leave a Comment

Help! They Lost the Data

Help! They Lost the Data

What can we do without reliability function estimates? FMEA? FTA? RCA? RCM? Argue about MTBFs and availability? Weibull? Keep a low profile? Run Admirals’ tests? Look for a new, well-funded project far from the deliverable stage? 

Ask for field data; there should be enough to estimate reliability and make reliability-based decisions, even if some data are missing. Field data might even be population data!

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George 1 Comment

Estimation of a Hidden Service-Time Distribution of an M(t)/G/∞ Self-Service System

Estimation of a Hidden Service-Time Distribution of an M(t)/G/∞ Self-Service System

(This is chapter 5 of User Manual for Credible Reliability Prediction – Field Reliability (google.com), cleaned up and typeset for AccendoReliaiblity Weekly Update.) 

The nonparametric maximum likelihood estimator for an M/G/∞ self-service time distribution function G(t) extends to nonstationary, time-dependent, Poisson arrival process M(t)/G/∞ systems, under a condition. A linearly increasing Poisson rate function satisfies the condition. The estimator of 1-G(t) is a reliability function estimate, from population ships and returns data required by generally accepted accounting principles. 

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George 1 Comment

Renewal Process Estimation, Without Life Data

Renewal Process Estimation, Without Life Data

At my job interview, the new product development director, an econometrician, explained that he tried to forecast auto parts’ sales using regression. His model was 

sales forecast = Sb(s)*n(t-s) + noise; s=1,2,…,t,

where b(s) are regression coefficients to be estimated, n(t-s) are counts of vehicles of age t-s in the neighborhood of auto parts stores. The director admitted to regression analysis problems, because of autocorrelation among the n(t-s) vehicle counts, no pun intended. 

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Reliability from Current Status Data

Reliability from Current Status Data

A computer company tiger team held a meeting to decide how to fix their laser printer ghosting problem. Bearings seized in the squirrel-cage cooling fan for the fuser bar. The fan bearing was above fuser bar, which baked the bearing. A fix  decision was made, voted on, and accepted. Party time. I asked, “How do you verify the fix?” Boo!

This an example of using current status life data. I checked status every laser printer laser-printer fan in company headquarters: operating or failed? Date of manufacture was encoded in the printer serial number, so I estimated the fan’s age-specific failure rate function, before the fix. Premature wearout was evident. Could I observe repaired or new printers at a later time and test the hypothesis that the problem had been fixed? Yes. 

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

User Manual for Credible Reliability Prediction

User Manual for Credible Reliability Prediction

The ASQ Reliability Division (RD), copyrighted the 2003 monograph “Credible Reliability Prediction” (CRP) but lost all copies circa 2014. I pestered the RD to let me republish CRP, because people asked “How do I make credible reliability predictions?” Copyright reversion to authors is accepted practice when a publisher no longer supports a document. 

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George 1 Comment

Credible Reliability Prediction?

Credible Reliability Prediction?

ASQ Reliability Division published “Credible Reliability Prediction” (CRP) in 2003. Harold Williams, Reliability Division monograph series editor, wrote, “[CRP] …delineates statistical methods that effectively extend MTBF prediction to complex, redundant, dependent, standby, and life-limited systems… This is the first text that describes a credible method of making age-specific reliability predictions…. This monograph presents insights and information inspired by real applications and [still] not covered in contemporary reliability textbooks.” 

[Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Nonparametric Forecasts From Left-Censored Data

Nonparametric Forecasts From Left-Censored Data

“Component D” had some failures in its first 12 months. How many more would fail in 36-month warranty? ASQ’s Quality Progress Statistics Roundtable published the data and Weibull analysis. The data included left-censored failure counts collected at one calendar time. The Weibull analysis included actuarial failure forecasts. This article describes nonparametric alternatives to Weibull and quantifies extrapolation uncertainty. The nonparametric forecasts are larger than the Weibull forecasts. Alternative extrapolations of nonparametric failure rates from data subsets quantify uncertainty. [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Actuarial Forecasts, Least Squares Reliability, and Martingales

Actuarial Forecasts, Least Squares Reliability, and Martingales

I learned actuarial methods working for the USAF Logistics Command. We used actuarial rates to forecast demands and recommend stock levels for expensive engines tracked by serial number, hours, and cycles. I had a hunch that actuarial methods could be applied to all service parts, without life data. [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Ergodicity, Toilet Paper, and Field Reliability

Ergodicity, Toilet Paper, and Field Reliability

Ergodicity means that cross-section probabilities equal longitudinal lifetime probabilities. (“Ergos” is Greek for “work.” Think of “ergonomics”.) Ergodicity means that we can estimate age-specific field reliability functions from cross-section data: ships (installed base) and returns (complaints, failures, service parts’ sales, etc.). Ships and returns provide information about lifetimes. Returns are the superpositions of failures of products or their parts started at different times. What does ergodicity have to do with toilet paper? [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Gozinto Theory and Parts’ Installed Base

Gozinto Theory and Parts’ Installed Base

Andrew Vázsonyi led an interesting life. He collaborated with mathematician Paul Erdös, he was co-founder of The Institute of Management Sciences, and he wrote “Which Door has the Cadillac: Adventures of a Real-Life Mathematician”. Around 1970, Andrew Vázsonyi interviewed for a teaching job in Sauder School of Business, University of British Columbia. During the job interview, he taught us Gozinto Theory. [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George 1 Comment

How Can You Estimate Reliability Without Life Data?

How Can You Estimate Reliability Without Life Data?

Myron Tribus’ UCLA Statistical Thermodynamics class introduced me to entropy, -Sp(t)ln(p(t)). (p(t) is the probability of state t of a system.) Professor Tribus later advocated maximum-entropy reliability estimation, because that “…best represents the current state of knowledge about a system…” [Principle of maximum entropy – Wikipedia] Caution! This article contain statistical neurohazards.

Claude Shannon wrote that entropy (log base 2) represents information bits, “…an absolute mathematical limit on how well data from the source can be losslessly compressed onto a perfectly noiseless channel.”  [Beirlant et al.]

Maximum likelihood estimation is one way to estimate reliability from data. It maximizes the probability density function of observed data, Pp(t), e.g., for observed failures at ages t. It is equivalent to maximize -Sln(p(t). Maximum entropy reliability estimation maximizes entropy -Sp(t)ln(p(t). That’s same as maximizing the expected value, -Sp(t)ln(p(t), of the log likelihood -ln(p(t). Fine, if you have life data, ages at failures t censored or not. [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Here’s the Data

Here’s the Data

Ralph Evans was editor of the IEEE Transactions on Reliability from 1969 until 2004. He was a very good editor for my 1977 article, and he used me as a reviewer, because I was critical of BS and academic exercises. Ralph moved to University Retirement Community, Davis, CA. He died in 2013, https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6587564. I wish I’d known he lived nearby so I could have visited and argued with him.

Ralph’s editorials [1 and 2] pled, “Data, Data, Oh Where Art Thou Data?” He wrote, “Field-data are largely garbage. I believe they deserve all the negative thinking possible.” “True field-data are wonderful-much better than fancy equations. Unfortunately, they are very difficult to get. Thus data from the field are largely garbage because they do not represent what really happened.” [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Firestone Tire Reliability Circa Year 2000

Firestone Tire Reliability Circa Year 2000

My wife and I were in Firestone-Walker Brewery (Buellton, California) after Solvang Danish Days. (That’s me playing in the Solvang Village band.) My wife was comparing an Adam Firestone photo on the wall with a man at a table. I was admiring a woman seated near the bar with balletic posture. The balletic woman picked up a pizza and delivered it to the man and sat with him. My wife went over and asked the man if he was Adam Firestone? He was, with his sister Polly. While my wife chatted with them, I did not engage, because I was responsible for FORD recalling the Firestone tire sizes that Firestone did NOT recall. [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

by Larry George Leave a Comment

Want Field Reliability, Without Life Data?

Want Field Reliability, Without Life Data?

Would you like the reliability of all your products and their service parts, without assumptions, in real environments, and with all premature failures, complaints, repairs, warranty expirations, preventive maintenance, changes, warranty extensions, etc.? Field reliability tells what really happens! [Read more…]

Filed Under: Articles, on Tools & Techniques, Progress in Field Reliability?

« Previous Page
Articles by Larry George
in the Progress in Field Reliability? article series

Join Accendo

Receive information and updates about articles and many other resources offered by Accendo Reliability by becoming a member.

It’s free and only takes a minute.

Join Today

Recent Articles

  • Top Five Challenges For Process Safety
  • 1702 Corrosion and Wear in Mine Water Pumps
  • Residual Stresses in Metals
  • Expect to Pass Validation using Accelerated Tests
  • Nomad at Last

© 2022 FMS Reliability · Privacy Policy · Terms of Service · Cookies Policy

This site uses cookies to give you a better experience, analyze site traffic, and gain insight to products or offers that may interest you. By continuing, you consent to the use of cookies. Learn how we use cookies, how they work, and how to set your browser preferences by reading our Cookies Policy.