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Weibull++ Standard Folio

Life Data Analysis Plots

Weibull++ includes multiple plot types you can use to visualize the results of your life data analysis. You can create plots by choosing Life Data > Analysis > Plot or by clicking the icon on the Main page of the control panel.

The scaling, setup, exporting and confidence bounds settings are similar to the options available for all other Weibull++ plot sheets. To learn how to customize a plot, see Plot Setup.

Tip: Weibull++ includes two additional plots you could use across all types of data folios: the overlay plot, which allows you to compare different data sets or distributions; and the side-by-side plot, which allows you to display different plots of a single data set all in a single window for easy comparison.

The following is a description of the different types of plots that can be created in a Weibull++ standard folio:

When the parameters have been calculated using rank regression analysis, the regression line is fitted to the data points on the plot in order to obtain the distribution parameters. Therefore, the plot can also be used to compare how different distributions fit a particular data set. The closer the regression line tracks the points on the plots, the better the fit.

In contrast, the maximum likelihood estimation (MLE) method obtains the solution of the line from the likelihood function, not by the plotting positions of the data points. Therefore, the line is not expected to track the points on the plot, and the plot should not be used to evaluate the fit of a distribution when using MLE.

The next figures show the rank regression analysis of single data set using a Weibull distribution and a lognormal distribution. As you can see, the probability plot shows that the Weibull distribution presents the better fit to this particular data set.

Weibull Probability Plot

Lognormal Probability Plot

You have the option to adjust the time intervals to get a good indication of how the data points are distributed. Note that if the histogram has intervals that are, in theory, infinitesimally small, the chart will result in a plot of the probability density function (pdf).

 

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