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Analytical Power
Data Types, Models, Statistical Tests
ReliaSoft's RGA 6 provides unparalleled analytical power for your reliability growth,
projections and fielded (repairable) systems analyses with a flexible array of data entry and analysis options
depending on the data and analysis types.
Supported Data Types
RGA's data entry spreadsheets support both developmental testing data and fielded systems data. This includes
time-to-failure (continuous), success/failure (discrete) and
reliability data, entered individually or in groups, cumulative or non-cumulative. You
can even define "gaps" for some data types to compensate for missing or
questionable data points.Specifically, you can use RGA to analyze:
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| Data from Developmental (Reliability Growth) Testing |
- Failure Times
- with or without
failure mode identification, classification and
effectiveness factors (for projections)
- cumulative or non-cumulative
- Grouped Failure
Times, within specified time intervals
- with or without
failure mode identification, classification and
effectiveness factors (for projections)
- Multiple Systems
with Known Equivalent Times (the time of the failure
plus the operating times of the other systems under
test)
- cumulative or non-cumulative
- Multiple Systems
with Unknown Equivalent Times, to be combined to form a single "equivalent" system for analysis purposes
- with or without the chronological date of each event
- with or without failure mode identification, classification and effectiveness factors (for projections)
- Sequential
Success/Failure from one-shot (pass/fail) tests
- Sequential Success/Failure
with Failure Mode Identification
- Grouped
Success/Failure per
Configurations
- cumulative or non-cumulative
- Reliability for different times/stages
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| Data from Fielded
Repairable Systems |
- Known start, end and failure times for multiple systems, to be combined to form a single "superposition" system for analysis purposes
- with or without the chronological date of each event
- with or without
failure mode identification, classification and
effectiveness factors (for projections)
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Statistical Models
RGA 6 supports all of the major reliability growth analysis models
and
RGA 6 PRO incorporates statistical models for
reliability growth projections and the analysis of fielded (repairable)
systems data. This includes new model
formulations developed by Dr. Larry
Crow exclusively for use in the RGA package.
Available models include:
- Developmental Testing Data
- Crow - AMSAA (NHPP) for continuous and discrete data.
- Crow Extended for continuous data with the required
failure mode classifications and effectiveness factors.
New formulation, only available in RGA 6
PRO!
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Duane for continuous and discrete data.
- Gompertz and Modified
Gompertz for discrete and reliability data.
- Logistic for discrete and reliability data.
- Lloyd Lipow for discrete and reliability data.
- Fielded Systems Data
Only available in RGA 6
PRO!
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Analysis
of success/failure (discrete) data with the Modified Gompertz model. Other data types and models are available.
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[Click to Enlarge]
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Parameter Estimation and Statistical Tests
Depending on the data/analysis type, Maximum Likelihood Estimation (MLE)
or Least Squares are used for parameter estimation.
In addition,
RGA 6 provides Chi-Squared and Cram'er von Mises (CVM) methods for goodness-of-fit testing (depending on the data type), as well as the
Common Beta Hypothesis (CBH) to indicate whether multiple systems should be combined into an "equivalent" or "superposition" system for analysis. The
Laplace Trend Test provides an indication of whether the system's reliability is improving, deteriorating or staying the same.
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Support for both
time-to-failure (continuous) and success/failure (discrete) data types, as well as reliability and
repairable systems data. |
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Statistical models include: -Crow-AMSAA (N.H.P.P.)
- Crow Extended
-Duane
-Gompertz
-Modified Gompertz
-Logistic
-Lloyd Lipow
-Power Law |
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Statistical tests
include: -Chi-Squared Goodness-of-Fit
- Cram'er von Mises (CVM) Goodness-of-Fit
-Laplace Trend Test
-Common Beta Hypothesis (CBH) |
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