Fred Schenkelberg — Thought Leader

Author of CRE Preparation Notes, Musings", NoMTBF, multiple books & ebooks>, co-host on Speaking of Reliability>/a>, and speaker in the Accendo Reliability Webinar Series.

This author's archive lists contributions of articles and episodes.

by Fred Schenkelberg Leave a Comment

How Do You Stay Current?

When I first started working in a factory as a shift supervisor, it seemed there was some type of formal training nearly every month. And we were expected to attend a conference once a year. Little did I know that was a great time to start working in industry. We enjoyed a lot of great training.

Later in my career and as the economy changed budgets for training slowly declined. Travel budgets also slipped away. I don’t have hard numbers, yet I suspect there is less company-sponsored professional development than 20 years ago.

As an engineering working in the reliability field, how do you keep up and learn what you need to know to accomplish your work? [Read more…]

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Murphy’s Law and Reliability

It always seems there are more red lights when I’m running late.

This comment and others similar to it caught my attention lately. Is it just Murphy’s Law or something else?

There is an element of luck or chance in many events during our daily lives. The same is true when producing products and the resulting reliability. A lot has to go right for the product to work for the customer.

When something isn’t going as expected, we have a comparison that gains attention. If the lights are red more often, in theory, when I’m running late, maybe the lights are not turning red more often, it’s just that we notice.

For product development, it’s noticing the items that are going well and failing that matter. As reliability professionals, we need to continue to practice being aware of what is expected and what actually happens. [Read more…]

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Spearman Rank Correlation Coefficient

This non-parametric analysis tool provides a way to compare two sets of ordinal data (data that can be rank ordered in a meaningful manner). The result, r_s, is a measure of the association between two datasets.

You may want to know if two reviewers have similar ratings for movies, or if two assessment techniques provide similar results. [Read more…]

by Fred Schenkelberg 13 Comments

Kendall Coefficient of Concordance

Comparisons for agreement

Let’s say we have data that is only rank order from two or more evaluators (people, algorithms, etc.) and we want to determine if the evaluators agree or not.

The agreement here meaning the results from one person or another are in agreement, or they are concordant. This is typically done with this non-parametric method for 3 or more evaluators. For a comparison of two evaluators consider using Cohen’s Kappa or Spearman’s correlation coefficient as they are more appropriate. [Read more…]

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The Learning and Teaching Route to Success

Reliability engineers learn basic tools and techniques most often from others with that knowledge. During our careers, we also continue to learn and often find ourselves teaching. Even when mentoring we find ourselves learning. Being a deliberate and active student and teacher is a great way to remain inquisitive and helpful.

Learning and teaching route to success

Formal education will make you a living; self-education will make you a fortune. [1]

Learning never stops. [Read more…]

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Three Considerations for Sample Size

Detecting a change or difference is often the aim of an experiment or set of measurements. We want to learn which vendor, process, or design provides a better result.

When we use a sample to estimate a statistic for a population we take the risk that the sample provides values that are not representative of the population. For example, if we use a professional basketball team to sample men’s height. We may conclude that the height of men in the general population is taller than the true population value. [Read more…]

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Successful Reliability Engineers Add Value

Value is:

the regard that something is held to deserve; the importance, worth,
or usefulness of something. [1]

As a reliability engineer, we work across the organization to bring a reliable product to market. The value of meeting the customer’s reliability expectations results in customer satisfactions, increased sales, and in some cases premium pricing.

We want a reliable product.

[Read more…]

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Mann-Whitney U Test

The U test permits the comparison of two samples to determine if they came from the same population or not. This non-parametric test can use ordinal data, meaning it is in some rank order without containing information about relative distances between ranks. [Read more…]

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Networked and Positive as a Reliability Engineer

Many elements help make a reliability engineer successful.Two such elements are knowing the right people to get the job done and generally being a positive and enjoyable person to be around.

[Read more…]

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Laplace’s Trend Test

A test to determine if the homogeneous Poisson model (HPP) is applicable given the data from an individual system is subject to the non-homogeneous Poisson model (NHPP).

This is an alternative test to using the Kendall-Mann Reverse Arrangement Test. [Read more…]

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Talent and Professionalism as a Reliability Engineer

My dictionary says that talented is “having a natural aptitude or skill for something.”

We learn reliability engineering and those who understand the range of tools and techniques useful for a given situation would be considered talented.

Everything is not solved by running a highly accelerated life test (HALT) or only conducting detailed failure analysis. Knowing when and why to apply a particular tool and using the tool effectively (i.e., when to use a Weibull distribution to model lifetime data and how to use the information to make decisions) are critical. [Read more…]

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Failure Modes and Mechanisms

When something fails, what should we do?

A natural question when something fails is

Why did it fail?

The answer is not always obvious or easy to sort out.

One of my favorite examples was on a circuit board that had a small burn mark where a component exploded off the board. The customer didn’t notice that missing part, our engineering team did that. [Read more…]

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Success as a Reliability Engineer

Whether by design or by accident some of us become reliability engineers. Making a career in reliability engineering relies on your ability to make a difference and to add value. Being successful as a reliability engineer, while creating reliable products, permits continuation and growth as a reliability professional.

[Read more…]

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Why Wait for Field Returns?

In an ideal world, our products and equipment will just work. They would not fail and would not require warranty claims, product returns, or repair.

Unfortunately, we make design mistakes, assembly errors, incur damage, or simply fail. The desired balance for most businesses is the cost of returns will not outweigh the profit of sales.

[Read more…]

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3 Steps NRTL Use for Product Safety

With any product development, there is a risk the features (benefit) come along with inherent dangers (risk). For example, a desktop computer includes the need for electrical power. Done improperly a person exposed to wall current and voltage could be seriously harmed. While unlikely the risk exists. [Read more…]