Useful Statistical Tools
Monte Carlo Simulation
Weibull++ continues to use Monte Carlo simulation for generating data sets that can be analyzed directly in a standard folio. You can also use the SimuMatic® utility to automatically perform a large number of reliability analyses on data sets that have been created via simulation. These simulated data sets and calculated results can be used to perform a wide variety of reliability tasks, such as:
- Experimenting with the influence of sample sizes and censoring schemes on analysis methods.
- Constructing simulation-based confidence bounds.
- Experimenting with confidence intervals for analyses performed with different distributions.
- Developing and evaluating test plans.
- Utilizing user-defined equations for risk analysis and probabilistic design.
Quick Parameter Estimator (QPE)
The Quick Parameter Estimator (formerly called the "Parameter Experimenter") has been redesigned and expanded. The QPE allows you to estimate the parameters of a statistical model based on what you know about the behavior over time. The tool still offers the familiar "Expert" view, which allows you to solve for one parameter if you know one unreliability point and the other parameter, or solve for all parameters if you know two unreliability points. The tool now offers a new "Wizard" view that allows you to bypass the statistical terminology and simply answer a series of questions about what you know from practical experience. The software will "translate" your answers into the inputs required to obtain the model parameters.
Life Comparisons and Stress-Strength Analysis
The software provides two tools designed for statistical comparison of data sets. The Life Comparison tool allows you to compare two data sets to determine whether items from the first set will outlast those of the second. The Stress-Strength comparison tool uses the same statistical approach to determine the probability of failure based on the probability of a specified "stress" data set exceeding a specified "strength" data set.
Both tools have been redesigned and enhanced in the Synthesis version. Now you can save individual analyses in the project for future reference, generate a pdf plot to visualize the comparison and obtain the confidence bounds on the calculated probability, if desired. We have also added a new integrated tool designed to support robust engineering methods by allowing you to solve for design parameters based on target reliability (e.g., determine the strength distribution needed to ensure that strength will exceed stress).
Quick Statistical Reference
The Quick Statistical Reference frees you from tedious lookups in tables by quickly returning results for commonly used statistical functions. Results include Median Ranks, Chi-Squared Values, Cumulative Binomial Probability, and many more. There is also a Polynomial Interpolation Function that allows you to enter known data points and then calculate Y for any given X value.
Non-Linear Equation Fit Solver and Root Finder
The software continues to offer two familiar statistical tools for working with non-linear equations.
- Redesigned with a more user-friendly interface, the Non-Linear Equation Fit Solver allows you to estimate the parameters of any user-defined non-linear equation. This gives you the flexibility to perform simple parameter estimation on statistical models other than the life distributions and life-stress relationship models available in standard folios. After you have solved the equation, the tool provides a plot to visualize how the data fit the function, and also makes it easy to calculate Y for any given X value.
- The Non-Linear Equation Root Finder allows you to quickly solve for the root of any user-defined non-linear equation. This helps you eliminate some of the guesswork of solving for the value of the unknown variable that makes the function be as close to zero as possible.