Abstract
Cognitive work analysis (CWA) techniques are the primary methods available for designers to obtain the knowledge required to create interfaces to complex systems involving cognitive work. There are a wide and growing variety of analysis methods available with a variety of claims for their relative strengths and weaknesses, but it is extremely rare for anyone actually to apply different analytic techniques to the same analysis problem. The work reported here begins to address this gap by directly comparing the information requirements produced by what are probably the 2 most commonly used analysis techniques-Rasmussen's (1985) Abstraction-Decomposition Space (ADS) or "Abstraction Hierarchy" and Shepherd's (1989) Hierarchical Task Analysis (HTA) technique. These 2 approaches were selected because each is well known in the literature, yet they rarely have been directly compared on a common problem. Our comparison shows that the techniques produce different yet complementary information about the interaction needs that human users of a system will have. Both approaches have strengths and weaknesses, but ultimately they reflect different perspectives on (and different avenues to) the knowledge needed for good system and interface design.