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Reliability Glossary

Reliability Growth Terms

AMPM
"AMPM" stands for "AMSAA maturity prediction model." This is an enhanced reliability growth model that allows the user to predict failure rates in future stages of development. This model allows the user to assess the effectiveness of proposed and implemented fixes in order to determine the future failure rate.

AMSAA model
"AMSAA" stands for "Army Material Systems Analysis Activity." This is a reliability growth model that uses a relationship between cumulative test time and cumulative failures to develop a reliability growth model.

Duane model
A reliability growth model similar to the AMSAA model that uses a relationship between cumulative test time and cumulative failures to develop a reliability growth profile.

Gompertz model
A reliability growth model that models reliability values at different stages of development, and produces an S-shaped reliability growth curve.

Lloyd-Lipow model
A reliability growth model based on the number of trials and successes at each stage of product development.

Modified Gompertz model
A reliability growth model that models based on a variation of the Gompertz model.

NHPP
"NHPP" stands for "non-homogeneous Poisson process," which is a simple parametric model used to represent events with a non-constant failure recurrence rate. This type of model is often used to model reliability growth and the reliability of repairable units.

Reliability growth
The analysis of the change in reliability over time, usually applied to products under development. Reliability growth analysis provides the means by which the reliability, mean life or failure rate is tracked over time, allowing the user to predict future reliability values based on the current rate of growth of the reliability measurement of interest.