Web-Based iTools
The iTools section is the newest addition to the weibull.com site. The iTools are Web-based computational utilities that provide quick statistical results. These tools are based on the same powerful computation engines that drive the Weibull++ life data analysis software package and they provide results directly through your Web browser. The following tools are currently available:

• Simple Weibull Analysis: Enter data and calculate the parameters for the two-parameter Weibull distribution.
• Rank Calculator: Obtain the rank value for a given percentage, sample size and order number.
• Quick Statistical Reference: Obtain values for commonly used statistical functions, such as cumulative binomial probability, student’s t values, chi-squared values, etc. Figure 1 displays the QSR iTool with a chi-squared value calculated with the click of a button.
• Exponential Design of Reliability Tests Calculator: Determine the test time required to obtain a given MTBF or Reliability, assuming an exponential distribution.

Other Reliability Analysis Tools
In addition to the new iTools section, the weibull.com site also provides other reliability analysis tools via the Web. For instance, hundreds of users have downloaded the probability plotting papers that are available in PDF format (*.pdf) from the site. Papers for the Weibull, lognormal, normal and exponential distributions are available. These files have been generated by the Weibull++ software and can be used to print high-quality papers for manual probability plotting. Practitioners can use the Rank Calculator iTool or obtain the required ranks from the rank tables provided on the site.

The weibull.com site also provides software tools designed to support ancillary reliability analyses. These tools were developed by ReliaSoft Corporation and are available for free download to registered users. One of these tools, the SimuMatic® utility, can be used to explore reliability life data analysis using Monte Carlo simulation. Some of the applications for this tool include the ability to construct simulation-based confidence intervals and to experiment with the influences of sample sizes and censoring schemes on analysis methods. Volume 2, Issue 1 of Reliability Edge includes an article that examines these and other applications for the utility. The SPRT tool, another free utility available from weibull.com, performs the calculations required for sequential probability ratio testing with the Weibull distribution. This testing and analysis method can be used to demonstrate compliance with a given reliability requirement using a minimum number of test units. Figure 2 displays the SPRT utility with a sample analysis.

Reliability eTextbooks
In addition to the growing collection of hands-on and application-oriented resources, weibull.com also provides an extensive array of theoretical references. One set of references, the Reliability eTextbooks, provide comprehensive treatments of fundamental reliability analysis subjects in a flexible Web-based format. These searchable online references provide table of contents, index and free text search capabilities to provide quick access to the specific information of interest. Reliability eTextbooks are currently available for:

• Life data analysis (Weibull analysis)
• Accelerated life testing data analysis, with an emphasis on quantitative accelerated life testing (QALT) analysis
• System reliability, maintainability and availability analysis, with an emphasis on reliability block diagram approaches
• Reliability growth analysis

Reliability References, Case Studies and Other Resources
Other references on weibull.com include:

• Quick Subject Guides: The site’s Quick Subject Guides provide a brief overview of some of the key topics in reliability engineering to provide a quick and easy-to-understand foundation in the subject. These references also provide suggestions for further, more detailed, research.
• Case Studies: The site provides access to case studies for subjects such as life data analysis and accelerated life data analysis. These case studies include step-by-step instruction for performing the analyses in ReliaSoft’s software packages.
• Reliability Publications: The site provides access to online versions of the Reliability Edge quarterly newsletter as well as the monthly Hotwire eMagazine. In addition, the site includes a comprehensive subject index to the articles in those publications.
• Research Papers: Scholarly research papers that have been published/presented by ReliaSoft’s R&D personnel are available for download in PDF format (*.pdf).
• Seminars and Training Guides: The site provides access to information on training seminars for reliability engineering and related subjects, as well as training guides in PDF format (*.pdf). The training guides include step-by-step examples for reliability analyses performed with ReliaSoft’s software products.
• Other Resources: Other resources provided by weibull.com include lists of recommended reliability books, reliability- and quality-related Web links, an online glossary of reliability terms as well as a complete “blueprint” for implementing a successful reliability program. Resources are added and improved on an ongoing basis.

Discussion Forum
The weibull.com site is provided as a service to the reliability community and, as such, features an interactive discussion forum designed to facilitate communication within the field. Discussion topics include a general reliability discussion, employment opportunities and questions/comments regarding ReliaSoft’s standard software products. These forums are open to everyone and no password is required. ReliaSoft personnel monitor and participate in the discussions.

Conclusion
The extensive array of reliability resources described in this article attracts thousands of visitors each month to weibull.com. The weibull.com site (shown in Figure 3) is updated and enhanced on an ongoing basis and ReliaSoft makes every effort to be responsive to requests from the reliability community. To make suggestions for improvement or to request additional references and tools, contact Webmaster@ReliaSoft.com or complete the simple form located on the Web at http://www.weibull.com/Feedback.