Statistics for Maintenance Modelling: Regression Modelling

# Summary¤

In this session we have seen how regression models can be used to model data where it is thought that lifetime depends on another variable or variables. Three key regression models were introduced that are often used in reliability modelling.

1. Accelerated life models; we saw how the rate of failure is ‘accelerated’ by some covariate, for example, the load.
2. Proportional hazards models, where the hazards at different values of the covariate, say load again, are in constant proportion over time.
3. Proportional odds models, where the odds at different values of some covariate, say load, are in constant proportion over time. Several plots were presented in order to aid identification of these models, i.e. which one would be appropriate for a particular data set.

Note that it is not necessary for you to be able to reproduce the theoretical underpinnings of these models, or plots, rather you understand the basic concepts of each model and plot, and when it is appropriate to use them. After all computers do fit these models for us.