Multi-tasking and Cost Structure, Implications for Design

I argue that it is not possible to accurately represent our task settings as close environments with a single well defined cost structure. Natural environments are places where many things are done, often at the same time, and often by many people. To appreciate the way such invariants of everyday life affect design I present a case study, a micro-analysis of espresso making at Starbucks to show the challenges facing a cost structure approach.