Calculations Settings

The Calculations page of RGA's Application Setup contains default settings that will be applied to calculated results when you create a new folio in RGA. Note that any of these configurable settings that are saved in an existing folio can be modified via the Item Properties window.

Precision to be Displayed on Calculations sets the math precision (number of decimal places) and the point at which the software will switch to scientific notation. For example, if the scientific notation tolerance is set to 5, then any number that is larger than 10⁵ will be displayed using scientific notation.
Failure Discounting applies only to the Discrete Sequential with Mode data type. Specify the confidence level that will be used to define the fractional decrease in failure value. (See Failure Discounting.)
Crow/Power Law Models applies only to calculations using the Crow-AMSAA (NHPP), Power Law, Crow Extended or Crow Extended - Continuous Evaluation models. Select whether to display the value of the power law parameter, Lambda, or the Weibull parameter, Eta, in the analysis results.
Duane Model applies only to calculations using the Duane model. Select whether to display the value of the A parameter (cumulative failure intensity) or the b parameter (cumulative MTBF) in the analysis results.
Crow Extended Model applies only to calculations using the Crow Extended or Crow Extended - Continuous Evaluation models.

Show Crow-AMSAA beta for beta = 1 hypothesis displays the value of the beta parameter for the Crow-AMSAA (NHPP) model in addition to the hypothetical value of beta calculated for the Crow Extended or Crow Extended - Continuous Evaluation models, as shown in the following example.

Allow EF values for BD modes with implemented fixes adds a second tab in the Effective Factors window when you are using the Crow Extended - Continuous Evaluation model. This allows you to record the effectiveness factors for BD modes that were fixed during testing. Note that this functionality is for your information only; it is not used in calculations.

Instantaneous MTBF/FI at the End of Development Testing sets whether the instantaneous MTBF and failure intensity at the end of the test will be shown in the analysis results with the term “demonstrated” (i.e., DMTBF/DFI) or “achieved” (i.e., AMTBF/AFI).
User Warnings
- Beta = 1 hypothesis is invalid displays a message when the beta = 1 hypothesis fails. This warning applies only to the Crow Extended or Crow Extended - Continuous Evaluation models.
- Model parameters out of range displays a message when the value of the k parameter (logistic model) or Alpha parameter (Lloyd-Lipow model) is less than or equal to zero. Negative values indicate that the analysis results may not be valid.
- Effectiveness factors of zero displays a message when one or more effectiveness factors equal to zero. This warning applies only to the Crow Extended or Crow Extended - Continuous Evaluation models.
Other Options

Use percents (not decimals) for reliability displays reliability values as percentages (e.g., 90) rather than decimals (e.g. 0.90). This applies to the Reliability data type only.
Data input is cumulative configures the data sheet for cumulative failure times, by default, instead of non-cumulative failure times. (See Cumulative vs. Non-Cumulative Data.)
Calculate unbiased beta removes the bias of the MLE estimate of the beta parameter, when applicable. An unbiased estimate will be labeled in the results as "Beta (UnB)" instead of "Beta." For more information, the "Unbiasing Beta for the Crow-AMSAA (NHPP) Model" article at: http://www.weibull.com/hotwire/issue141/hottopics141.htm demonstrates how the bias is corrected for Crow-AMSAA (NHPP). This is also applicable to the Crow Extended, Crow Extended - Continuous Evaluation and power law models.

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