Estimating degradation in real time and accelerated stability tests with random lot-to-lot variation: A simulation study
✍ Scribed by Robert T. Magari
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 174 KB
- Volume
- 91
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
The effect of different lot-to-lot variability levels on the prediction of stability are studied based on two statistical models for estimating degradation in real time and accelerated stability tests. Lot-to-lot variability is considered as random in both models, and is attributed to two sourcesÐvariability at time zero, and variability of degradation rate. Real-time stability tests are modeled as a function of time while accelerated stability tests as a function of time and temperatures. Several data sets were simulated, and a maximum likelihood approach was used for estimation. The 95% con®dence intervals for the degradation rate depend on the amount of lot-to-lot variability. When lot-to-lot degradation rate variability is relatively large (CV ! 8%) the estimated con®dence intervals do not represent the trend for individual lots. In such cases it is recommended to analyze each lot individually.