Accendo Reliability

Your Reliability Engineering Professional Development Site

  • Home
  • About
    • Contributors
    • About Us
    • Colophon
    • Survey
  • Reliability.fm
  • Articles
    • CRE Preparation Notes
    • NoMTBF
    • on Leadership & Career
      • Advanced Engineering Culture
      • ASQR&R
      • Engineering Leadership
      • Managing in the 2000s
      • Product Development and Process Improvement
    • on Maintenance Reliability
      • Aasan Asset Management
      • AI & Predictive Maintenance
      • Asset Management in the Mining Industry
      • CMMS and Maintenance 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
      • RCM Blitz®
      • ReliabilityXperience
      • Rob’s Reliability Project
      • The Intelligent Transformer Blog
      • The People Side of Maintenance
      • The Reliability Mindset
    • on Product Reliability
      • Accelerated Reliability
      • Achieving the Benefits of Reliability
      • Apex Ridge
      • Field Reliability Data Analysis
      • Metals Engineering and Product Reliability
      • Musings on Reliability and Maintenance Topics
      • Product Validation
      • Reliability by Design
      • Reliability Competence
      • Reliability Engineering Insights
      • Reliability in Emerging Technology
      • Reliability Knowledge
    • 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
      • Institute of Quality & Reliability
      • Integral Concepts
      • Learning from Failures
      • Progress in Field Reliability?
      • R for Engineering
      • Reliability Engineering Using Python
      • Reliability Reflections
      • Statistical Methods for Failure-Time Data
      • Testing 1 2 3
      • The Manufacturing Academy
  • eBooks
  • Resources
    • Accendo Authors
    • FMEA Resources
    • Glossary
    • Feed Forward Publications
    • Openings
    • Books
    • Webinar Sources
    • Podcasts
  • Courses
    • Your Courses
    • Live Courses
      • Introduction to Reliability Engineering & Accelerated Testings Course Landing Page
      • Advanced Accelerated Testing Course Landing Page
    • Integral Concepts Courses
      • Reliability Analysis Methods Course Landing Page
      • Applied Reliability Analysis Course Landing Page
      • Statistics, Hypothesis Testing, & Regression Modeling Course Landing Page
      • Measurement System Assessment Course Landing Page
      • SPC & Process Capability Course Landing Page
      • Design of Experiments Course Landing Page
    • The Manufacturing Academy Courses
      • An Introduction to Reliability Engineering
      • Reliability Engineering Statistics
      • An Introduction to Quality Engineering
      • Quality Engineering Statistics
      • FMEA in Practice
      • Process Capability Analysis course
      • Root Cause Analysis and the 8D Corrective Action Process course
      • Return on Investment online course
    • Industrial Metallurgist Courses
    • FMEA courses Powered by The Luminous Group
    • Foundations of RCM online course
    • Reliability Engineering for Heavy Industry
    • How to be an Online Student
    • Quondam Courses
  • Calendar
    • Call for Papers Listing
    • Upcoming Webinars
    • Webinar Calendar
  • Login
    • Member Home
  • Barringer Process Reliability Introduction Course Landing Page
  • Upcoming Live Events
You are here: Home / Articles / Are We Teaching Reliability All Wrong?

by Fred Schenkelberg Leave a Comment

Are We Teaching Reliability All Wrong?

Are We Teaching Reliability All Wrong?

Let’s Demand Better Reliability Engineering Content

Teaching reliability occurs through textbooks, technical papers, peers, mentors, and courses. The many sources available tend to use MTBF as a primary vehicle to describe system reliability.

What has gone wrong with our education process?

MTBF Abounds in Books and Lectures

From tutorials by college professionals at RAMS to numerous ‘reliability engineering’ textbooks, the discussion equates reliability with MTBF. The way to measure or describe the reliability of something is MTTF for non-repairable systems or MTBF for repairable systems (like that bit of semantics matters).

Just use an average. It’s good enough.

A good textbook does not mention MTBF; a great lecture avoids the use of MTBF. IMHO

When I confronted a professor on why a major portion of a tutorial on reliability statistics focused on MTBF, she said it was a great way to teach the concepts of distribution properties without worrying too much about the math. It was merely a mechanism to teach other concepts.

The lecture did not spend much time applying those concepts to real problems. It did not explain the use of MTBF (and the exponential distribution) was never to be used in the real-world set of examples to focus on key concepts. It left me and others in the room with the idea that MTBF was the way to describe reliability.

The same conversations with book authors.

MTBF is Easy

The ASQ CRE exam is rife with problems using MTBF (or MTTF). Why? – Because it is easy and quick to test calculations based on MTBF and the exponential distribution.

Sure, it’s easy, but it’s not something we should be good at. Aren’t we supposed to be good at solving real problems that are not easy? How about creating a certification exam that evaluates what we should know and do at work, not what is considered easy?

Students/Engineers Need to Understand MTBF

As I rant on about abolishing MTBF in more than one setting, I encounter the rebuttal that students and engineers need to know about it, if for no other reason than that it is out there.

Sure, MTBF is on data sheets, test reports, parts count software outputs, etc. It is everywhere.

I agree that students and engineers need to understand the folly of MTBF, the lack of information it contains, and the inability to use it for meaningful decision-making. What I really want is for students and engineers to learn to automatically insist on more information, data, and evidence, all leading to an understanding of reliability (probably of success over time…).

When I hear someone ask for MTBF, I ask them what they really want to know. What they seek, when asking for MTBF, is never served or supported by knowing MTBF. We need to learn, and teach, reliability engineering to help each other ask better questions and solve real problems.

Stop This Vicious Cycle Now

If I use existing literature and teachings on reliability engineering to prepare a new book on the topic, I would likely feel compelled to include MTBF. I won’t, other than to warn the reader to not use it at all.

You should do the same.

If in a class or tutorial where the instructor mentions MTBF, ask them when they will begin talking about something useful concerning reliability. Go ahead, you can say I urged you to ask.

If reading a book that drones on about MTBF testing and confidence intervals for time or failure truncated testing, send the author a note on when and under what conditions would this technique every be useful. Ask then to provide case studies and evidence that the underlying failure mechanisms involved are actually best fit by the exponential distribution. Ask them to justify spending more than one sentence of this expensive book on such drivel.

Go ahead, ask for rationale and justification. Ask for a better education.

If enough people stand up and say, ‘Hold on—when in the real world is the use of MTBF ever useful?’, we just may get some professors and authors to provide meaningful content.

How have you challenged the use of MTBF? If you haven’t, why not? What is holding you back?

Filed Under: Articles, NoMTBF

About Fred Schenkelberg

I am the reliability expert at FMS Reliability, a reliability engineering and management consulting firm I founded in 2004. I left Hewlett Packard (HP)’s Reliability Team, where I helped create a culture of reliability across the corporation, to assist other organizations.

« Basics of 5 Whys
Reliability Estimation with Kaplan-Meier Nonparametric Method »

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

The NoMTBF logo

Devoted to the eradication of the misuse of MTBF.

Photo of Fred SchenkelbergArticles by Fred Schenkelberg and guest authors

in the NoMTBF article series

Recent Posts

  • Gremlins today
  • The Power of Vision in Leadership and Organizational Success
  • 3 Types of MTBF Stories
  • ALT: An in Depth Description
  • Project Email Economics

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

© 2025 FMS Reliability · Privacy Policy · Terms of Service · Cookies Policy