Decreasing Failure Rates and Related Issues in the Social Sciences.

Studies conducted in various social disciplines discovered that, the longer individuals remain in a state, the lower the chances of their leaving that state in subsequent periods. "Inertia" of this kind is accumulated, for example, in durations of tenure in an organization and at a residence, abstention from crime after release from prison, and durations of strikes. This concept of inertia can be formalized by utilizing measures of residual durations that are commonly used in reliability. We refine concepts of inertia to investigate the rate of inertia accumulation, as captured by the various measures. We show how desirable "second-order" negative aging properties can provide some guidance in the selection of an appropriate parametric distribution to model empirical duration data.