[Editor's Note: The tools mentioned in this article are now integrated directly into the
in the Non-Parametric RDA folio, the SimuMatic utility and the "Weibull
SPRT" analysis workbook report template that is installed with the
The weibull.com website provides
free software tools designed to accomplish specific reliability tasks. These
tools are available via the Web at
These free software tools are of commercial
quality, created by ReliaSoft Corporation. However, unlike ReliaSoft’s
standard software, the free tools are made available without a technical
support commitment from ReliaSoft and with minimal or no product
documentation. Available tools include:
RDA Utility for
Recurrent-Events Data Analysis and Plotting
ReliaSoft's RDA Utility has been
designed for recurrent event data analysis and plotting in accordance with
the techniques described by Dr. Wayne Nelson in Recurrent- Events Data
Analysis for Repairs, Disease Episodes, and Other Applications,
published in 2003 in the ASA-SIAM Series on Statistics and Applied
SimuMatic® for Life Data
allows you to explore reliability life data analysis using Monte Carlo
simulation. With SimuMatic, life data analyses are performed a large number
of times on data sets that have been created using Monte Carlo simulation.
Multiple results are available for each simulation. This utility can assist
the analyst to better understand life data analysis concepts, experiment
with the influences of sample sizes and censoring schemes on analysis
methods, construct simulation-based confidence intervals, better understand
the concepts behind confidence intervals and/or design reliability tests.
Weibull SPRT Tool for
Sequential Probability Ratio Test Analysis
ReliaSoft's Weibull SPRT is a
sequential probability ratio test utility that uses Weibull sequential
testing and allows you to test samples in a sequential manner. The SPRT
utility performs all calculations required in order to determine whether to
accept or reject the hypothesis that the samples are from a given Weibull
life distribution and meet a given reliability requirement.
- Simple Weibull Analysis: Obtain
parameters for the 2-parameter Weibull distribution, using your data.
- Rank Calculator: Obtain ranks
given a sample size and order number.
- Quick Statistical Reference:
Obtain values for commonly used statistical functions (chi-squared, ranks,
- Exponential Design of Reliability
Tests Calculator: Obtain test time to demonstrate an MTBF (or
reliability) assuming an exponential distribution.
These web-based iTools are available at: