Non-Parametric RDA Folio

The non-parametric RDA folio is based on the mean cumulative function (MCF). This analysis provides a plot of the MCF to illustrate the average number of recurring failures of a system, or a group of systems, over a given period of time (or distance, cycles, etc.). The MCF can be used to evaluate whether the number of failures increases or decreases over time, to predict the future number of failures or to compare different data sets from different designs, operating conditions, production periods, etc. The ReliaWiki resource portal has more information on the MCF at: http://www.reliawiki.org/index.php/Non-Parametric_Recurrent_Event_Data_Analysis.

Non-Parametric RDA Data Sheet

To create a non-parametric RDA folio, choose Home > Insert > Non-Parametric RDA, or right-click the Repairable Systems folder in the current project explorer and choose Add Non-Parametric RDA on the shortcut menu.

The following picture shows an example of the non-parametric RDA folio data sheet.

Evaluating Results

To analyze the data set, choose Recurrent Event Data > Analysis > Calculate or click the icon on the control panel.

Note that this will also sort the data set by system ID and then by time to event.

To view the results, click the Show Results (...) button to open the Results window, as shown next.

The Time column displays the system ages, sorted in chronological order, that were entered for the failure events. The Sample MCF column shows the average number of failures at each particular age.

The Variance column indicates the amount of uncertainty in the MCF value. This is also used to obtain the 1-sided confidence bounds that are displayed in the Lower Limit and Upper Limit columns. These three columns are available only if you have selected the Calculate Confidence check box in the control panel and specified a confidence level.

The MCF values and the confidence bounds can also be displayed in an MCF plot in order to visualize the behavior of the recurring failures. To view the MCF plot, choose Recurrent Event Data > Analysis > Plot, or click the icon on the control panel.

The following plots show some examples of the different MCF shapes.

Related Topics and Links