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Quick Calculation Pad (QCP)

QCP Calculations and Plots for Crow Extended

RGA includes a Quick Calculation Pad (QCP) for computing useful metrics, as well as multiple plots that allow you to visualize the results of your analyses. This topic describes the calculations and plots you can obtain from data sheets analyzed with the Crow Extended model.

Note: When you analyze data from multiple systems, RGA combines the data to create a single representative system (i.e., equivalent system, superposition system or cumulative timeline, depending on the data type). Any plots generated for the combined data set and subsequent analyses via the Quick Calculation Pad will be based on the resulting representative system. See Times-to-Failure Data from Multiple Systems and Fielded Data for more information about how the software combines the data for analysis.

QCP Calculations

You can open the Quick Calculation Pad (QCP) by choosing Growth Data > Analysis > Quick Calculation Pad or by clicking the icon on the control panel.

To perform a calculation, select the appropriate option and enter any required inputs in the Input area, then click Calculate. For more detailed information about all the options available in the QCP, see Quick Calculation Pad (QCP).

The Basic Calculations tab of the QCP includes the typical calculations for traditional reliability growth analysis (e.g., cumulative/instantaneous MTBF and expected number of failures). These calculations are applicable only when your data set includes BC failure modes. (See QCP Calculations and Plots for Traditional RGA.)

On the Extended Calculations tab, the available calculations will vary depending on whether you’re analyzing failure times or mixed (discrete) data. For failure times, the calculated values will be mean time between failures (MTBF) and failure intensity (FI). For mixed data, the values will be reliability and probability of failure. Most of these calculations are applicable only when your data set includes BD failure modes.

Plots

You can create plots by choosing Growth Data > Analysis > Plot or by clicking the icon on the control panel.

This section describes the types of plots you can create for the Crow Extended model. The scaling, setup, exporting and confidence bounds settings are similar to the options available for all other RGA plot sheets. (See Plots.)

Once again, the available calculations will vary depending on whether you’re analyzing failure times or mixed (discrete) data. For failure times, the calculated values will be mean time between failures (MTBF) and failure intensity (FI). For mixed data, the values will be reliability and probability of failure.

The plots described next apply to data sets that include at least some BD modes. Some of these plots apply specifically to data sets that consist entirely of A/BD modes (e.g., when you use the Crow Extended model to analyze fielded data), where the analysis assumes that there is no reliability growth during the observation.

To learn more about how the failure times are combined, see the following topics:

 

Tip: RGA includes two additional plot utilities you can use across all types of data: the overlay plot, which allows you to compare different data sets or models; 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.

 

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