Resumen de Why do the failure rates decrease?

M. D. Berradé, Francisco Germán Badía Blasco, Clemente Antonio Campos Sáez

• It is quite plausible that any device or system reliability shows an increasing failure rate (IFR) as age, use or both may cause it to wear out over time. Nevertheless, explaining a decreasing failure rate, which means an improvement as time goes by, is far from intuitive. Mixtures of lifetime distributions turn out to be the most widespread explanation for this "positive ageing". In this work, the proportional hazard rate (PHR) is revisited and related to an exponential mixture. We also analyse the effect of mixing on the patterns of dependence on time that the mixture exhibits.