alone, are particularly susceptible to missing errors. Limited Perspective - Humans cannot see all there is to see. The inability of the human mind to perceive all facts pertinent to a decision challenges problem-solving. Susceptibility To Emotional/Social Factors - Anger and embarrassment adversely influence team and individual performance. Fatigue - People get tired. Physical, emotional, and mental fatigue can lead to error and poor judgment. Presenteeism - Some employees will be present in the need to belong to the workplace despite a diminished capacity to perform their jobs due to illness or injury. Analysis techniques A variety of methods exist for human reliability analysis (HRA). Two general classes of methods are those based on probabilistic risk assessment (PRA) and those based on a cognitive theory of control. PRA-based techniques One method for analyzing human reliability is a straightforward extension of probabilistic risk assessment (PRA): in the same way that equipment can fail in a power plant, so can a human operator commit errors. In both cases, an analysis (functional decomposition for equipment and task analysis for humans) would articulate a level of detail for which failure or error probabilities can be assigned. This basic idea is behind the Technique for Human Error Rate Prediction (THERP). THERP is intended to generate human error probabilities that would be incorporated into a PRA. The Accident Sequence Evaluation Program (ASEP) human reliability procedure is a simplified form of THERP; an associated computational tool is Simplified Human Error Analysis Code (SHEAN). More recently, the US Nuclear Regulatory Commission has published the Standardized Plant Analysis Risk - Human Reliability Analysis (SPAR-H) method to take account of the potential for human error. Cognitive control based techniques Erik Hollnagel has developed this line of thought in his work on the Contextual Control Model (COCOM) and the Cognitive Reliability and Error Analysis Method (CREAM). COCOM models human performance as a set of control modes—strategic (based on long-term planning), tactical (based on procedures), opportunistic (based on present context), and scrambled (random) - and proposes a model of how transitions between these control modes occur. This model of control mode transition consists of a number of factors, including the human operator's estimate of the outcome of the action (success or failure), the time remaining to accomplish the action (adequate or inadequate), and the number of simultaneous goals of the human operator at that time. CREAM is a human reliability analysis method