Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIED43 - AC/243(Panel-8)TR7Volume 175. From Table 3.1 it can be seen that the majority of techniques available for functionalanalysis and function allocation provide only nominal or ordinal measurements. Those analyseswhich do have a direct link to system performance requirements use interval or ratio scalemeasures. It can be concluded that the techniques used for function allocation are not yet mature,and that the complete sequence of analyses must be completed and reiterated if they are toaddress system performance.3.3 CONCLUSIONS FROM REVIEW OF HUMAN ENGINEERINGANALYSIS TECHNIQUES76. The work of the RSG has shown that a wide variety of human engineering analysistechniques are available. The review covered thirty-one typical examples: it is not an exhaustivereview of all the existing variants of those techniques. More extensive lists of techniques areavailable if required (Bogner, 1989).77. The techniques fall into six categories of analysis: mission analysis functionanalysis, function allocation, task analysis, performance prediction, and interface and workspacedesign. Normally, the classes of technique should be used in sequence. The actual starting pointin the sequence may depend on project constraints and priorities and the extent to which humanengineering has been accepted into the project. In selecting the techniques to use at each stage ofanalysis, users are advised to work backwards through the chain of analyses; e.g., if one of theprime goals is to run a SAINT simulation then the analysis should develop a description of thetask network from OSDs or a similar technique.78. Half of the techniques reviewed are similar to, or related to, techniques used forsystems engineering analysis. Obviously, some techniques are used more than others (seeSection 2.1). Applications depend on the size of the project, position in project cycle, and scopefor innovation in the design. There are few reports of the application of these techniques tosimple systems. Applicability of a specific technique also depends on the chain of analyses, asoutlined above.79. The effective use of the techniques is based on a decomposition of the system designproblem area which results in defined functions, sub-systems, or states. The characteristics ofthese functions, sub-systems, or states are then defined and validated. The items are thencombined to predict the system performance and operator/maintainer workload. In general, it isassumed that the prediction of system performance is valid if it is based on the validatedperformance of sub-systems.80. Most analyses require few resources and can be performed with paper and pencil,but nearly all benefit from use of a computer for tracking, editing and analysing the data. There isa need for such programs to be integrated, rather than stand-alone, so that data are not re-enteredmany times. Few computer tools have been developed to date, but they are growing in number.81. The quality assurance aspects of the various techniques are not widely understood.Managers and practitioners should pay more attention to quality assurance factors.82. The link from human engineering analyses to system performance requirements isnot explicit, in most cases. The majority of the "classic" human engineering analyses do not havea direct relationship to system performance requirements and, to be made relevant, they requireadditional analysis of system performance. Those analyses which have a direct link to systemperformance requirements use interval or ratio scale measures. The least mature techniques, interms of their relationship to system performance, are those used for function allocation.