Publication date: 07/30/2020

## Cause Combination

The Cause Combination report lets you fit and compare different failure time distributions (Fi(x)) for the various causes. Different distributions are available based on selections that you have made in the launch window. Negative and zero-failure times are not allowed.

The default plot is based on a Linear scale and shows the following:

Nonparametric estimates (Kaplan-Meier-Turnbull) for the uncensored data values and their confidence intervals. The confidence intervals are represented by horizontal blue lines.

Fits of cumulative failure distributions (Fi(x)) to each of the causes. The initial distribution is the one that you selected in the launch window. If you selected Individual Best, the best distribution is computed for each group and these fits are shown. (This selection can be time-intensive.) If you selected Manual Pick, the initial Distribution is Nonparametric for all groups and nonparametric fits are shown. A legend appears to the right of the plot.

The Aggregated cumulative failure distribution, F(x), represented by a black line. This function is computed based on the selected cause distribution. If a nonparametric distribution is specified for a cause, the aggregated cumulative failure distribution extends only as far as the final time observation for that cause.

As you interact with the report, statistics for the aggregated model are re-evaluated.

The Cause Combination report contains these elements:

Scale

Specifies the probability scale for the plot’s vertical axis. Change the Scale illustrates how changing the scale affects the distribution fit.

Omit

Check a box to remove the fit for the corresponding cause. Use this when a particular cause has been fixed. The Aggregated model updates to reflect the removal of the failures due to that cause. Omit Competing Causes illustrates the effect of omitting causes.

Cause

Lists the causes in the Cause column.

Distribution

Lists the available distributions for each cause. To change the distribution for a specific failure cause, select the distribution from the Distribution list. Click Update Model to show the new distribution fit on the plot. The Cause Summary report is also updated.

Count

Gives the number of observations with the given failure cause.

Update Model

Shows the selected distributions in the plot; updates the Cause Summary report with the selected models; adds the selected model as the most recent one in the Individual Causes report.