Analysis Techniques For Man-Machine Systems Design

NATO UNC LAS SIFIE.DAC/243(Panel-8)TR7V olu me I- 52 -analyses must cut across different trade-off study areas. This will require improvements tohuman engineering analysis techniques to make them compatible with parametric studies. Thework of NATO AC/243 Panel-8/RSG. 2 1 on "Liveware Integration" may contribute to definingthe extent of this problem.4.4.2 User centred system design99. McLaughlin (1987) has reported an approach which emphasizes iterativedevelopment through user evaluation of a prototype. His "user engineering methodology" hasbeen combined with traditional system engineering techniques to develop complex man-machinesystems. The approach is intended to gather data about the potential system users andincorporate those data into the design process as early as possible. The methodology, whichparallels the approach recommended for human factors engineering, emphasizes, defines,validates, and maintains the user's view of the system being developed. Similar approaches havebeen called "user centred system design" (Norman & Draper, 1986), and "usability engineering"(Whiteside, 1988). Typically these approaches involve the development of specifications whichinclude "usability" requirements, development and iteration of user procedures. evolution of thedesign through iteration. and testing the design using "usability"' criteria. as it evolves.-A genericapproach includes seven steps:(1) mission and operational concept definition(2) user/system data extraction(3) user analysis (establishment of a representative profile of the user)(4) task analysis(5) human-computer interface analysis(6) prototype validation(7) users' design review100. This approach parallels that recommended for the application of human engineeringdescribed earlier in this report. The approach also parallels the systems engineering process,thereby providing the opportunity for collaboration with systems engineers and developers.Typically, however, the user analysis is not performed in military systems engineering studies.This analysis is conducted prior to task analysis to derive a model of the user group. This isbecause customer requirements for complex man-machine systems are often subjective, vague,incomplete, or unknown (McLaughlin. 1987; Pressman. 1987). A representative profile of theuser group is formed from results of interviews, from observations, and from cognitive. workstyle and personality measures. It should be noted that user analysis has been placed on thehuman-machine systems research agenda only recently and it will be a long time before methodsappropriate for design are established. However, what is important is to be aware that designersimplicitly assume a user profile when designing systems. and this profile should be formulatedmore explicitly.101. In the user centred approach to design, extensive prototyping, with a lot ofdeveloper/end-user interaction, is substituted for the preparation of detailed requirementsdocuments. McLaughlin (1987) claims that "new procurement procedures are needed in order toinsure that these activities are conducted early. Formal documentation deliverables in contractsmust initially yield to the delivery of prototypes, and the analysis surrounding their developmentand trial use." Following the user design review more traditional (formal. top-down) systemdesign methods are used.102. In summary, more widespread use of user centred design approaches and useranalysis may require developments or modifications to existing task analysis techniques. TheNATO UNCLA.SSI.FIEED- 52 -