Introduction to the Delphi Method

As reliability professionals, we are in the business of estimating or forecasting the reliability performance of our product, equipment, or system. While we use a range of tools to analytically make these estimates, sometimes we do not have sufficient data or information.

One method is to ask another person that has knowledge of the particular technology, use conditions, or whatever is hampering our work. If you ask two people you most like will get two different answers. If you ask 10, 10 different answers.

One way to work with a group of subject matter experts is to conduct a structured communication technique called the Delphi Method. [Read more…]

by Fred Schenkelberg Leave a Comment

Building and Using Pareto Charts

You may have heard of the 80/20 rule. The idea is that 80% of the wealth is held by 20% of the population. As an Italian economist, Vilfredo Pareto made this observation that became generalized as the

Pareto Principle: 80% of outcomes are due to 20% of causes

For field returns, for example, we may surmise that 80% of the failures are due to 20% of the components, for example. This principle helps us to focus our work to reduce field failures by address the vital few causes that lead to the most, or most expensive, failures. [Read more…]

by Fred Schenkelberg Leave a Comment

Check Sheet: Capture Data Quickly

There are two common uses for a check sheet. First, to summarize historical data, or second, to collect observations. A byproduct of creating a check sheet is team agreement on definitions of categories and observation procedures.

The investment is minimal other than thinking about how you want to view the data, and what data to collect. [Read more…]

by Fred Schenkelberg 1 Comment

Censored Data and CDF Plotting Points

Reliability testing and data collection is a messy business.

We rarely receive perfect data where all units involved have a precise time to failure record. Sometimes we do not the precise time to failure information or some of the units are still operating.

The data is censored.

There are a few common types of censoring, each of which has statistical techniques to appropriately account for the unknown elements. [Read more…]

by Richard Coronado 3 Comments

FRACAS

The Failure Reporting and Corrective Action System (FRACAS) is a closed-loop process whose purpose is to provide a systematic way to report, organize and analyze failure data. Implementation of a FRACAS has increasingly become commonplace within an industry. The requirement for implementation of some type of FRACAS within a DoD program was first established in 1985 with MIL-STD-2155. However, in 1995 that standard was reestablished with no changes to content as a handbook, MIL-HDBK-2155, and was recommended as guidance. Today, multiple software solutions exist that provide all the functionality required of a FRACAS. [Read more…]

by Fred Schenkelberg 5 Comments

M and A Sample Questions

Just a couple of sample questions from deep in the body of knowledge this week.

Which of the following can be evaluated with dye penetrant methods? [Read more…]

by Fred Schenkelberg 2 Comments

Reading CDF Plots

First the Question:

Fred,
Early in the FMEA lecture you worked through a homework problem and you mentioned that a cdf may not be linear (hence the reason for giving three points in a reliability goal). Can you give an example of two of things you’ve seen with non-linear cdf’s? I’ve only done limited reliability testing at this point, but everything I’ve done and every example I’ve ever seen have had linear cdf’s.
Thanks,
John

And, my response: [Read more…]

by Fred Schenkelberg Leave a Comment

EAM & CMMS Systems, 10 times more data in the system or 10 time less done with the data available?

EAM & CMMS Systems, 10 times more data in the system or 10 time less done with the data available?.

A nice short article about the problem of data, data, too much data.

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Introduction to the Delphi Method

Building and Using Pareto Charts

Check Sheet: Capture Data Quickly

Censored Data and CDF Plotting Points