5 Ways Your Reliability Metrics and Fooling You
We measure results. We measure profit, shipments, and reliability.
The measures or metrics help us determine if we’re meeting out goals if something bad or good is happening, if we need to alter our course.
We rely on metrics to guide our business decisions.
Sometimes, our metrics obscure, confuse or distort the very signals we’re trying to comprehend.
Here are five metric based mistakes I’ve seen in various organizations. Being aware of the limitations or faults with these examples may help you improve the metrics you use on a day to day basis. I don’t always have a better option for your particular situation, yet using a metric that helps you make poor decisions, generally isn’t acceptable.
If you know of a better way to employ similar measures, please add your thoughts to the comments section below. Continue reading 5 Ways Your Reliability Metrics and Fooling You
The Variety of Statistical Tools to Support Your Decision Making
My wife and I moved to a new home last year. We have yet to organize our tools.
The bedroom and kitchen are now organized. We, for the most part, can find the sweater or pan that we’re seeking.
No so for our tools in the shop. We have an assortment of hand tools for painting, home maintenance, yard work, and woodworking. In our previous home, we had the tools on pegboards, on shelves, in cabinets. We could find the right tool for the job at hand quickly. We’ve avoided the tool aisle at the hardware store recently, as we were sure we had the tool we need in the jumbled mess in our garage already. Still haven’t found it, though.
Have you noticed the number of statistical tools available? It’s like visiting a well-stocked tool store. There are basic tools like trend charting and advanced tools like proportional hazard models. Let’s explore the available tools a little so you can quickly find the right tool for the question or problem you are facing today. Continue reading The Variety of Statistical Tools
Two people have shaped how I guess an answer.
Their comments and guidance have tailored how to form a quick estimate, my ability to articulate a hunch and the effectiveness of those guesses.
You probably guess or make a rough estimate regularly. How good is your gut feel? Do you keep track and score yourself?
Making an estimate should be second nature for you. It’s not something to do in public, too often. The practice can aid you in numerous ways. Continue reading The Rule of 3 Significant Digits
Teaching Reliability is Part of Your Role
Nearly everyone I’ve ever met doesn’t like their toaster to fail.
It will, and that is a bummer, as the quick and easy way to warm up the morning toast will be thwarted.
Failures happen. As reliability engineers, we know that failures happen. Helping others to identify potential failures, to avoid failures or to minimize failures is what we do best.
It is out ability to teach others about reliability engineering that allows us to be successful. Continue reading Teaching Reliability is Part of Your Role
Math, Statistics, and Engineering
In college, Mechanics was a required class from the civil engineering department. This included differential equation.
Luckily for me, I also enjoyed a required course called analytical mechanics for my physics degree. This included using Lagrange and Hamiltonian equations to derived a wide range of formulas to solve mechanisms problems.
In the civil engineering course, the professor did the derivation as the course lectures, then expected us to use the right formula to solve a problem. He even gave us a ‘cheat sheet’ with an assortment of derived equations. We just had to identify which equation to use for a particular problem and ‘plug-and-chug’ or just work out the math. It was boring. Continue reading Math, Statistics, and Engineering
The Dirge of the MTBF Bias
We use our biases every day to make choices.
We select the beige sweater because we have a color bias concerning our sweaters.
Many of our biases help us quickly make decisions. We rely on biases to move through the day. Many of our biases are under the surface, unconsciously guiding our daily decisions. Mostly, biases are good or at least inconsequential.
The problem is the bias that shields us from achieving our goals. Continue reading The Dirge of the MTBF Bias
Book Review: An Elementary Guide to Reliability
If you sort your Amazon search on ‘reliability engineering’ by price: low to high, you may find some interesting titles available for free or maybe a few pennies. Not one to resist a chance to fill another bookcase, it’s been a bit of spending spree.
One of the reasons, I am interested in older titles is to determine why MTBF is so prevalent today. So far, still looking and learning along the way.
There are many great books in our field. Sure, some are older. Some are not at all useful or helpful.
This book review is the first in what may become a monthly addition to the NoMTBF blog.
Today’s review is on the book, An Elementary Guide to Reliability (3rd) Third Edition, by G. W. A. Dummer and R. C. Winton. Continue reading Book Review: An Elementary Guide to Reliability
When Do Failures Count?
One technique to calculate a product’s MTBF is to count the number of failures and divide into the tally of operating time.
You already know, kind reader, that using MTBF has its own perils, yet it is done. We do not have to look very far to see someone estimating or calculating MTBF, as if it was a useful representation of reliability… alas, I digress.
Counting failures would appear to be an easy task. It apparently is not. Continue reading When Do Failures Count?
Sample Size and Duration and MTBF
If you have been a reliability engineer for a week or more, or worked with a reliability engineer for a day or more, someone asked about testing planning. The conversation may have started with “how many samples and how long will the test take?”
You have heard the sample size question.
Continue reading Sample Size and Duration and MTBF
Learn to Notice MTBF Everyday
Did you notice the speed limit signs in your neighborhood today?
If like me, you went about your commute or regular travels relatively blind. You watched for the neighbor’s dog that jumped into the road last week, yet didn’t register seeing the speed limit sign.
It’s a cognitive burden to notice the mundane or known. Continue reading Learn to Notice MTBF Everyday
The 3 Best Reasons to Use MTBF
This may seem an odd article for the NoMTBF site. Stay with me for a moment longer.
Over the years of speaking out on the perils of MTBF, there has been some push back. A few defend using MTBF. Here are three of the most common (maybe not exactly the best, per se) reasons to use MTBF. Continue reading The 3 Best Reasons to Use MTBF
Illuminating MTBF’s Lack of Information
Here’s a simple illustration of how MTBF oversimplifies data concealing essential information.
By convention, we tend to use MTBF for repairable data. That is fine.
You may also be aware of my dislike for the use of MTBF, for many different reasons. If you find yourself suggesting your organization, customer, industry or whomever to stop using MTBF, you may want to use this simple example to illustrate the ‘value’ of MTBF. Continue reading Illuminating MTBF’s Lack of Information
A Quick MTBF Search Reveals Distressing Results
I was preparing to write this article and wondered how many search hits would appear for MTBF? So, opened Google and did an MTBF search. It is a common if misunderstood, acronym.
Beyond the 5,200,000 Google search results, it was the first page results that got me thinking. Keep in mind that Google often serves up a combination of what it thinks you are seeking and which sites have been useful for others.
Let’s break down what you find when you do an MTBF search. Continue reading MTBF Search Result Sadness
4 Questions to Ask When Confronted with MTBF
MTBF comes up a bit too often. When it does I have found rolling my eyes and arguing against using MTBF is not very effective.
So, what should a knowing reliability professional do instead?
Let’s explore four questions that you can ask that may help others find the value in no longer talking about MTBF. Continue reading 4 Questions to Ask When Confronted with MTBF
Replace After MTTF Time To Avoid Failures – Right?
Received a short question last week. The person writing seems to already know the answer, yet asked:
If we replace an item after a duration equal to the MTTF value, we would avoid failures, right?
Well, no, most likely not, was my response. What is your response? How would you answer this question? Continue reading Replace After MTTF Time To Avoid Failures – Right?