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How Good is MTBF as a Metric?

Let’s look at the characteristics of a sound reliability metric and how MTBF is not true or beneficial. A metric should be true, beneficial, and timely. We’ll start with a rock climbing analogy.

A bolted hanger along a rock climbing route is often a welcome site. It provides the climber safety (clipping the rope to the bolt), direction (this is the way), and confidence. Does MTBF as a metric do the same for your organization?

As climbers, we count on the bolts to provide support in case something goes wrong or we need to rest along the route.

A reliability metric is often used in the same way as a climbing bolt. The measure, whether MTBF, Reliability, or Failure Rate, assures that the product’s reliability performance is as expected.

The organization’s profits are or will be safe. The development team uses the measures to guide design and supply chain decisions. The measure provides confidence to the organization regarding meeting customer expectations around reliability.

Note: This first article in the NoMTBF campaign was published on April 1st, 2009. Thus, we’ve been at this and making progress for a long time and come a long was since starting the NoMTBF campaign. I am looking forward to your comments, contributions, and suggestions.

Fred

At first, MTBF seems like a commonly used and valuable measure of reliability. Trained as a statistician and understanding the use of the expected value that MTBF represented, I thought, ‘Cool, this is useful.’

Then, the discussions with engineers, technical sales folks, and other professionals about reliability using MTBF started. And the awareness that not everyone, and at times it seems very few, truly understood MTBF and how to properly use the measure.