Weibull Analysis

Weibull Analysis


The statistical analysis of an item’s failure data is widely regarded as one of the most accurate techniques for assessing its reliability in a specific application or environment. Though there are many different statistical distributions (e.g., exponential, lognormal, etc.), the Weibull distribution is especially useful because of its ability to characterize a wide range of potential data trends. More specifically, it can be fit to a dataset exhibiting an increasing, constant or decreasing failure rate, a unique feature that separates the Weibull distribution from its counterparts. This feature also allows the Weibull distribution to mimic other statistical distributions, and is the reason why it is often used as a first approximation for fitting a collection of failure data.

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Product Description

The series name has a double meaning:
(1) the spelling of the name r-e-l-e-a-s-e indicates that the series is intended to “release“ the non-expert down the path to reliable products and
(2) the complementary terms “REL” with “ease”, implying the series goal of “reliability made easy.”

Of course, reliability success is seldom easy, requiring expertise and tailoring with tradeoffs addressing life-cycle costs and other issues, but we hope that the series will help those not familiar with reliability practices understand the basics.

While it is unlikely that the reader will become an instant expert in reliability by reading the RELease guides, it is likely that he/she will gain a better appreciation of the basic tools that lead to designing and building reliability into products and systems. The number of pages in each guide is intentionally limited to address only the basics, with comprehensive authoritative references listed for those wanting to know more. The initial set of guides will be continuously expanded in the future. Please let us know how the series can be improved to meet your needs in introducing reliability to the non-expert, or suggest other topics you would like to see developed.

Additional information

File Type:



Paul Lein





Publication Date:

July 2013

Table of Contents

1. What is a Weibull Analysis       2
2. Weibull Analysis Terminology       4
  2.1. Data Types     7
  2.2. Failure Modes     8
3. Performing a Weibull Analysis       9
  3.1. Plotting the 2-Parameter Weibull     12
    3.1.1. Distribution Analysis – Assessing the Fit to the Data   16
4. Troubleshooting a Bad Fit       20
  4.1. S-Curves     23
5. Weibull Analysis Reliability Prediction       25
  5.1. Reliability Prediction with Multiple Distributions     26
6. For More Information       27
7. Appendix       28

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