Weibull Parameters Pane for a Parametric Life Data Set
When a parametric life data set is selected in the LDA Navigator, you supply the basic parameters required for this type of life data analysis (LDA) in the Weibull Parameters pane. The following table describes all parameters that can appear in this pane for parametric LDA.
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Parameter
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Description
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Data type
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The type of data to analyze. Choices are Exact Times, Interval, and Free Form. The default is Exact Times. The selection for this parameter and the status of Suspensions and Grouped affect the table columns shown in the Weibull Data Points pane. For more information, see Weibull Data Points Pane for a Parametric Life Data Set.
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Suspensions
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Indicates whether the data set contains only failures or both failures and suspensions. This checkbox is unavailable if Free Form is selected as the data type. When it is cleared (default), only failures are included. When it is selected, both failures and suspensions are included. For more information, see Suspensions.
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Grouped
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Indicates whether the data is grouped. This checkbox is unavailable if Free Form is selected as the data type. When this checkbox is cleared (default), the data is not grouped, which means that each data point refers to a single failure or suspension. When this checkbox is selected, the data is grouped, which means that you can enter the number of failed units and/or suspended units for each time interval.
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Distribution
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The distribution to use to model failure times. Choices are Weibull, Lognormal, Normal, Gumbel- (Lower), Gumbel+ (Upper), Exponential, Rayleigh, Gamma, Logistic, and Log-logistic. The default is Weibull. For more information, see Failure and Repair Distributions. As described in Best Fit Distribution Analysis, you can perform best fit distribution analysis to determine which of these distributions best fits your data.
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Model
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The model to use in the analysis. The choices available depend on the distribution selected. For more information, see Models Per Distribution. If Competing Failure Modes is selected as the model for the Weibull, lognormal, normal, exponential, or Rayleigh distribution, additional parameters become available. For more information, see Competing Failure Modes.
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Calculation results
The parameters that can be calculated or specified for each distribution/model combination differ. Calculated results appear in this area once the data set has been calculated. To use a specific value for a parameter, you select Fixed? and then enter the value. For more information, see Fixed Parameter Values.
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