The MTBF Stories You Tell Can Cause Change

Stories communicate well. We have been telling stories long before the invention of writing or the internet. The MTBF stories we tell communicate our ideas, suggestions, and recommendations.

There are differences between good and poor stories. How you tell a story matters as well as the subject of the story. Now, MTBF stories may not be the most thrilling or entertaining, yet there are stories on MTBF topics that matter.

Let’s explore using the power of story to cause those around us to better understand and avoid the use of MTBF.

1. The MTBF is Bad Story

For someone that asks about MTBF, wants to talk about MTBF, or only knows and uses MTBF, this story may provide the needed ‘slap in the face’ (‘wake up call’ or insight) to look at MTBF as something other than reliability.

Simply telling someone that MTBF is bad doesn’t work. You need to provide support, evidence, and examples. In general, select a story that fits the current situation.

If someone asks you for your product’s MTBF, you may respond with another question, “What do you really want concerning reliability performance?”. This may lead to discussion about the actual reliability requirements they have in mind, or it may result in a puzzled look and a pause. You can then tell them a story about meeting customer exceptions and how product reliability is an important element of customer satisfaction. MTBF by comparison doesn’t provide the information they need, thus would not meet their needs well.

2. The MTBF Leads to Poor Decisions Story

This one is an easy story to tell as there are many examples available. It is also a story you should have ready as most of the time when someone is talking or asking about MTBF they are either going to make a decision or gathering information for others to make a decision.

Now, let’s assume that decision-makers would prefer to make the right decision for the given set of options available to them. If they need to select a component from one of two vendors, the wrong decision involves not enjoying the benefits of the better choice. The reliability of a component in your application is often considered when selecting a vendor. If only MTBF is used for the comparison, it certainly increases the chance of making the wrong decision. Comparing two data sheets MTBF values is little more than comparing two random numbers, plus it provides no information about the nature of expected failures over time (increasing or decreasing). Having and comparing time to failure distributions is much more informative than MTBF, thus improving the chance of selecting the right vendor.

Comparison is not the only decision adversely impacted by MTBF. If the decision to start production and shipments of a product is based on MTBF, it is likely to shield, hide, or obscure reliability issues due to the use of parts count or reliability testing based on the assumption of a constant hazard rate. Ignoring the expected reliability performance information does not change the actual field performance; therefore, get the best available information for your decision-making.

Other decisions may include readiness of a new design concept, effectiveness of a design or process improvement, or the purchase decision of your customers. Illustrating how MTBF provide inadequate information leads to making poor decisions more often who’ll help you and your team ask for better information and make informed reliability based decisions.

3. The MTBF Misunderstanding Story

There are more ways to misunderstand MTBF than there are MTxx acronyms. A common one is that MTBF represents minimum failure-free time. A quick story about the math and probability of failure over any given hour, then over a year, is generally enough to dispel this misunderstanding.

If someone uses MTBF as a synonym for reliability, a quick story on the definitions of the two terms may be handy. Maybe a story of how you once confused the two terms to your detriment.

If someone is simply assuming a constant hazard rate (or we’re in the ‘flat part of the curve’, thus MTBF is alright, a story about how making that assumption without checking if the assumption is true leads to very poor decisions.

In each case, using a story instead of a tutorial will help them actually hear your advice. They grasp the message and begin to avoid using MTBF.

My Favorite MTBF Story

The best stories I hear about MTBF are the ones from you about moving others off using MTBF, company policies that basically avoid using MTBF, educational or reminder pieces that shape an organization’s culture, and avoiding the use of MTBF.

The best stories of successful improvements to reliability programs by moving the reliability discussion away from the use of MTBF.

What is your favorite story? What is your success story? Add your story to the comments section below or send it to me directly at fms@nomtbf.com