Discrete degradation modeling using generalized mixed effect model

Degradation modeling is an effective approach for reliability assessment and predicting of remaining useful life in order to investigate the relation between failure time and degradation of a system or unit. The possibility of an association between degradation of the unit during the time and the effects of covariates on degradation processes should be taken into account in the model to improve the explanatory capabilities of degradation models. Sometimes, the exact amount of degradation could not be observed because of time, cost, and measurement tools limitations. Therefore, approximate degradation values can be compared with a critical threshold. In this paper, the degradation processes modeled with a generalized linear mixed-effect model in order to take into account the correlation between times. Also, maximum likelihood estimation and Bayesian estimate of parameters are derived.