In the Best Fit Distribution window, the Analysis page specifies the distributions to consider in the best fit analysis. By default, all supported distributions are selected. For a Weibull parametric life or warranty data set, the many distributions shown in the following figure are supported. For an ALT life data set, only three choices are supported: Weibull, Lognormal, and Exponential. The Weibull choice for an ALT life data set refers to the two-parameter model. You can click Select All or Clear All to select or clear all distributions and then customize your selections from there.

When you click Analyze on any property page in the Best Fit Distribution window, the selected distributions are analyzed to determine how well they fit the data points in the data set. For a Weibull parametric life or warranty data set, settings specified on the Options page affect the analysis, For more information, see Options Page (Weibull Module Only). Once the analysis is complete, the Analysis page is shown so that you can view the ranking results for selected distributions in the Rank column.

If a distribution other than the one selected for this data set has a higher ranking, both a Change button and a message indicating the distribution with the best fit are shown. To change to this distribution, you click Change. However, you might first want to review the results calculated on the Details page. For more information, see Details Page.

If a selected distribution is excluded from the analysis because of settings on the Options page or because supplied data or parameter values are invalid, it displays a dash (-) for Rank. This value is left blank for any distribution that you excluded from the analysis.

For an ALT data set, the name of the last column is LKV because the log likelihood method is always used to determine rankings. For a Weibull data, the name of the last column depends on what is selected for Ranking Criteria on the Options page. The following table displays the column name shown for each selection. For more information, see Options Page (Weibull Module Only).