Reliability HotWire: eMagazine for the Reliability Professional
In this issue:

Issue 14, April 2002

*Hot Topics
*Reliability Basics
*Tool Tips
*Hot News
*From the Edge
*Share Your Experience

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Hot Topics  
Financial Applications for Weibull Analysis
Reliability engineering may be described as the use of applied statistics for engineering evaluation purposes. Naturally, the statistical techniques incorporated in reliability engineering can be used for many other purposes. One field that employs many of the same statistical techniques is that of financial analysis. In this article, we will look at one of the ways Weibull analysis (i.e. statistical analysis with the Weibull distribution) can be used in a financial context by examining its utility in conducting intangible asset valuation. Potential applications for intangible asset valuation include credit card default rates, season ticket renewal rates for sports and entertainment venues, stock brokerage accounts and life insurance. This article uses the example of a newspaper's subscription accounts to explore the methods and results of this analysis type.

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Reliability Basics  
The purpose of this section is to offer background and advice to the novice reliability engineer.

Characteristics of the Weibull Distribution
In the last several issues of Reliability HotWire, we looked at how distributions are defined and how common reliability metrics are derived. In this issue, we will take a closer look at a specific distribution that is widely used in life data analysis - the Weibull distribution. Named for its inventor, Waloddi Weibull, this distribution is widely used in reliability engineering and elsewhere due to its versatility and relative simplicity. 

To read more, see 

Tool Tips  

The Tool Tips section addresses helpful hints and frequently asked questions about ReliaSoft software products.

  • How is the repair time determined when using subdiagram blocks in BlockSim RBDs?

  • How do I change the user name and company information in Weibull++ 5.0?

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Hot News
*    MSG-3 Maintenance Program Creator Released - ReliaSoft's MPC 3, an MSG-3 compliant maintenance program creator, was released in March, 2002. Developed with Honeywell Aircraft Engines & Systems Group, this software package is specifically designed for the aerospace industry. For more information, see
*    Next Seminar in Tucson, May 20 - 24 - The next ReliaSoft "Master the Subject, Master the Tools" seminar will be held in Tucson from May 20 - 24, 2002 at the Sheraton Hotel and Suites. For more information on course content and how to register, see
*    ReliaSoft at MRO - ReliaSoft will be participating at the Maintenance, Repair and Overhaul (MRO) Conference and Exhibition to be held April 9 - 11, 2002 at the Phoenix Civic Plaza and Convention Center in Phoenix, Arizona. ReliaSoft will have a booth in the vendors' area where you can get information on ReliaSoft's products and services. For more details, see
*    ReliaSoft at SAE  - ReliaSoft would like to thank those of you who stopped by the ReliaSoft booth in the vendors area during the recent SAE 2002 World Congress in Detroit, Michigan. We hope we helped contribute to making this a productive and interesting symposium for you.
*    New Resources on - Recent additions to ReliaSoft's reliability resource Web site,, include a System Reliability Online Reference and a handy subject index for the articles published in Reliability HotWire and Reliability Edge. Whenever you have reliability related questions, be sure to turn to for the answers!
From The Edge  
In addition to the monthly Reliability HotWire, ReliaSoft publishes Reliability Edge, a printed journal that includes articles and information related to the field of reliability engineering. Articles of interest in the current edition:
  • Introduction to Accelerated Testing Types - For a variety of reasons, manufacturers may wish to obtain reliability test results more quickly than they can when the data comes from products operating under normal use conditions. They may use accelerated life tests to capture life data for the product under accelerated stress conditions, which cause the units to fail more quickly. Performed correctly, accelerated testing can significantly reduce test times, resulting in reduced time to market, lower product development costs and lower warranty costs, as well as other benefits. See
  • Limitations of the Exponential Distribution for Reliability Analysis - The unsupported assumption that most reliability engineering problems can be modeled well by the exponential distribution is still widely held. In a quest for simplicity and solutions that we can grasp, derive and easily communicate, many practitioners have embraced simple equations derived from the underlying assumption of an exponential distribution for reliability prediction, accelerated testing, reliability growth, maintainability and system reliability analyses. However, the situations in which the exponential distribution may be appropriately applied are not as common as some would have you believe. See
Share Your Experience
Reliability Specification Experiences Wanted
Reliability specifications are a central component of most reliability analyses. Despite their central importance, there is wide variation within industry as to the format and meaning of reliability specifications. In many cases, there are serious deficiencies in the specifications on which manufacturers base important business decisions. In a future issue of our printed newsletter, the Reliability Edge, we will examine the reliability specifications that are commonly used in industry today. We invite you to participate by sharing non-confidential/non-proprietary information about the reliability specifications that you work with in your day-to-day efforts. Do you have experience with particularly effective reliability specifications? Have you struggled to educate decision makers in your organization about the inadequacies of the specifications that they have adopted? Have you received specifications from a client that just do not make sense?
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