Failure Rate/MTBF

Failure rate is the most commonly used term in reliability and related engineering interests, yet it is still not well understood by perhaps the majority of those using it. Indeed, more than one reliability treatise wrongly defines failure rate as a conditional probability density, i.e., wrong by the accepted criterion of what constitutes any probability density. The fact that these two concepts are by no means the same is clarified and made more precise. Mean time between failures and dimensionality are also briefly considered.