and probabilistic design (Monte Carlo Methods/DOE). The material or component can be re-designed to reduce the probability of failure and to make it more robust against such variations. Another common design technique is component derating: i.e. selecting components whose specifications significantly exceed the expected stress levels, such as using heavier gauge electrical wire than might normally be specified for the expected electric current. Common tools and techniques Many of the tasks, techniques, and analyses used in Reliability Engineering are specific to particular industries and applications, but can commonly include: Physics of failure (PoF) Built-in self-test (BIT) (testability analysis) Failure mode and effects analysis (FMEA) Reliability hazard analysis Reliability block-diagram analysis Dynamic reliability block-diagram analysis Fault tree analysis Root cause analysis Statistical engineering, design of experiments – e.g. on simulations / FEM models or with testing Sneak circuit analysis Accelerated testing Reliability growth analysis (re-active reliability) Weibull analysis (for testing or mainly "re-active" reliability) Thermal analysis by finite element analysis (FEA) and / or measurement Thermal induced, shock and vibration fatigue analysis by FEA and / or measurement Electromagnetic analysis Avoidance of single point of failure (SPOF) Functional analysis and functional failure analysis (e.g., function FMEA, FHA or FFA) Predictive and preventive maintenance: reliability centered maintenance (RCM) analysis Testability analysis Failure diagnostics analysis (normally also incorporated in FMEA) Human error analysis Operational hazard analysis Preventative/Planned Maintenance Optimization (PMO) Manual screening Integrated logistics support Results from these methods are presented during reviews of part or system design, and logistics. Reliability is just one requirement among many for a complex part or system. Engineering trade-off studies are used to determine the optimum balance between reliability requirements and other constraints. The importance of language Reliability engineers, whether using quantitative or qualitative methods to describe a failure or hazard, rely on language to pinpoint the risks and enable issues to be solved. The language used must help create an orderly description of the function/item/system and its complex surrounding as it relates to the failure of these functions/items/systems. Systems engineering is very much about finding the correct words to describe the problem (and related risks), so that they can be readily solved via engineering solutions. Jack Ring said that a systems engineer's job is to "language the project." (Ring et al. 2000) For part/system failures, reliability engineers should concentrate more on the "why and how", rather that predicting "when". Understanding "why" a failure has occurred (e.g.