with the discretion to meet the demands of the job in a variety of ways that suit their preferences or the particular needs of the moment. Finally, for the reasons already discussed, work domain analyses also provide workers with the support they need to recover from errors.
Two points are worth highlighting from this comparison. First, work domain analyses are absolutely essential for complex sociotechnical systems. They provide a way of supporting worker adaptation to novelty, thereby addressing the criterion of safety, and they provide discretion--not complete freedom--to workers, thereby addressing the criterion of health. Second, because they have complementary strengths and weaknesses, it would be useful to include both work domain analysis and constraint- based task analysis techniques in a single, integrated framework for work analysis. The framework described in the remainder of this book achieves this goal by including a work domain analysis phase (see chap. 7) and a constraint-based task analysis phase (see chap. 8) in one integrated, overarching framework.
What type of work analysis is appropriate for complex sociotechnical systems? In this chapter, we evaluated the suitability of normative approaches to work analysis in the form of task analysis. We learned that the vast majority of existing task analysis techniques are instruction based. Yet, such techniques are not well suited for complex sociotechnical systems because they underestimate context-conditioned variability, and if used, can lead to unusable or ineffective computer information systems. Thus, most existing task analysis techniques are not very useful for our purposes. Constraint-based task analysis techniques are better suited for complex sociotechnical systems. Moreover, they are more likely to lead to improvements in flexibility, productivity, worker health, and on-the-job learning. However, they are not capable of dealing with the demands imposed by unanticipated events. Fortunately, work domain analyses provide a basis for dealing with such events. Thus, a work analysis framework for complex sociotechnical systems should include both work domain analysis and constraint-based task analysis techniques. The bottom line is that constraint-based task analysis techniques are necessary, but they are far from sufficient. In the next chapter, we see if additional insights can be garnered from descriptive approaches to work analysis.