rates, failure modes and design strength. The FMEDA technique considers: All components of a design, The functionality of each component, The failure modes of each component, The effect of each component failure mode on the product functionality, The ability of any automatic diagnostics to detect the failure, The design strength (de-rating, safety factors) and The operational profile (environmental stress factors). Given a component database calibrated with field failure data that is reasonably accurate , the method can predict product level failure rate and failure mode data for a given application. The predictions have been shown to be more accurate than field warranty return analysis or even typical field failure analysis given that these methods depend on reports that typically do not have sufficient detail information in failure records. Failure rate in the discrete sense The failure rate can be defined as the following: The total number of failures within an item population, divided by the total time expended by that population, during a particular measurement interval under stated conditions. (MacDiarmid, et al.) Although the failure rate, , is often thought of as the probability that a failure occurs in a specified interval given no failure before time , it is not actually a probability because it can exceed 1. Erroneous expression of the failure rate in % could result in incorrect perception of the measure, especially if it would be measured from repairable systems and multiple systems with non-constant failure rates or different operation times. It can be defined with the aid of the reliability function, also called the survival function, , the probability of no failure before time . , where is the time to (first) failure distribution (i.e. the failure density function). over a time interval = from (or ) to . Note that this is a conditional probability, where the condition is that no failure has occurred before time . Hence the in the denominator. Hazard rate and ROCOF (rate of occurrence of failures) are often incorrectly seen as the same and equal to the failure rate. To clarify; the more promptly items are repaired, the sooner they will break again, so the higher the ROCOF. The hazard rate is however independent of the time to repair and of the logistic delay time. Failure rate in the continuous sense Calculating the failure rate for ever smaller intervals of time results in the (also called hazard rate), .