Why the plan doesn't hold

Most studies of plans and situated work have applied ethnographic methods and and thus fail to provide any quantitative insight into the extent of this phenomenon. We present a study of planning and executing operations in an operating suite. Quantitative analysis of log data reveals the extent to which operation schedules are carried out as planned, and qualitative studies reveal the reasons behind changes to the plan, the consequences of such changes, and the strategies used to cope with them. 67% of the plan is changed and only 56% of all operations are planned ahead. We discuss how operation schedules are subject to "continuous planning", and how this needs to be supported by technology.