What Does ‘Lifetime’ as a Metric Mean

14750331216_6c7a719566_oWhat Does ‘Lifetime’ as a Metric Mean

We talk about lifetimes of plants and animals. Also, you may talk about the lifetime of a product or system.

I expect to have safe and trouble free use of my car over its lifetime. Once in a while I find a warranty that says it is guaranteed over my lifetime — for as long as I own the blender, for example. Continue reading “What Does ‘Lifetime’ as a Metric Mean”

What should we use instead of MTBF?

Giving a presentation last week and asked if anyone uses an 85/85 type test, and a couple indicated they did. I then asked why?

The response was – just because. We have always done it, or it’s a standard, or customers expected it. The most honest response was ‘I don’t know’.

They why is the test being done? Who is using the information for a decision? What is the Continue reading “What should we use instead of MTBF?”

The language we use matters

During RAMS this year, Wayne Nelson made the point that language matters. One specific example was the substitution of ‘convincing’ for ‘statistically significant’ in an effort to clearly convey the ability of a test result to sway the reader. As in, ‘the test data clearly demonstrates…’

As reliability professionals let’s say what we mean in a clear and unambiguous manner.

As you may suspect, this topic is related to MTBF. Simply saying Continue reading “The language we use matters”

Do not want equipment failures

I am a rock climber. Climbing relies on skill, strength, knowledge, a bit of luck, and good gear. Falling is a part of the sport and with the right gear the sport is safe.

I do not know, nor want to know, the MTBF (or MTTF) of any of my climbing gear. Not even sure this information would be available. And, all of the gear I use does have a finite chance of failing every time the equipment is in use. Part of my confidence is the that probability of failure is really low. Continue reading “Do not want equipment failures”

true, beneficial and timely

 

How Good is MTBF as a Metric?

A bolted hanger along a rock climbing route is often a very welcome site. It provides the climber with safety (by clipping the rope to the bolt); with direction (this is the way); and, with 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 or Reliability or Failure Rate, provides a sense of assurance that the product in question is performing as expected.

The organizations profits are or will be safe. The development team uses the measures as a guide for design and supply chain decisions. And, the measure provides confidence to the organization related to meeting customer expectations around reliability. Continue reading “true, beneficial and timely”

First Impressions

At first MTBF seems like a commonly used and useful 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.

Continue reading “First Impressions”