Incidental factor analysis

Systems ergonomics Failure modes and effect analysis Fault tree analysis Incidental factor analysis (IFA) Hammer 1972 Meister 1971 Leplat 1978... 

Both the integrative model by Smillie Ayoub (1975) and the deviation concept by Kjellen (1984a) connect the general systems theory to the sequencing and energy models of accident causation. They encompass technical, organizational and human components of the system. Various methods of system safety analysis (e.g. fault tree analysis, incidental factor analysis) support the identification of technical and human deviations as well as the analysis of the conditions and consequences of these deviations. From the discussion of near misses and conflicts it became clear that frameworks of accident causation should cover all kinds of incidents, thus becoming frameworks of incidents. 

Figure 10.3 The responses of three hypothetical participants in a trial. Patient A has a good response, B a minimal improvement and C drops out as condition is deteriorating. In this case, in a LOCF analysis, overall symptom deterioration will be underestimated by the size of the arrow and the treatment will appear better, especially with large numbers of dropouts. However, depending on the disorder, the opposite is possible if drop-outs are due to improvement or incidental factors then these patients may also improve and sometimes those deteriorating/improving after drop-out will be equal. The point is, we just don t know what happened to these people.

Accident or mishap deviation models as used in system safety processes can permit analysis of events in terms of deviations. The value assigned to a system variable becomes a deviation whenever it falls outside an established norm. When measuring system variables, these deviations can assume different values depending on the situation. Hazard control policies and procedures should detail any specified requirements. A deviation from a specified requirement could result in a human error for failure to follow procedures. Therefore, we must consider incidental factors as deviations from an accepted practice. An unsafe act relates to a personal action that violates or deviates from a commonly accepted safe procedure. Time functions as the basic dimension in a system deviation... 

Third, if a weight is only incidental to the overall result of an accurate quantitative analysis, then it need not be made on an analytical balance. This means that if the weight measurement to be performed has no bearing whatsoever on the quantity of the analyte tested, but is only needed to support the chemistry or other factor of the experiment, then it need not be measured on an analytical balance. 

The physical environment within a crystal, of course, is not identical to that in solution or in a living cell. A crystal imposes a space and time average on the structure deduced from its analysis, and x-ray diffraction studies provide little information about molecular motion within the protein. The conformation of proteins in a crystal could in principle also be affected by nonphysiological factors such as incidental... 

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