In relation to an investment, a decision unit is a model of the investment containing sufficient data to make a decision.  The decision must be able to be made on a discrete basis, and may be either dependent or independent of other possible decisions. An organization will usually have decision units with differing scope and size, time frames, periodicity and account level detail depending upon: The decision maker’s position in the organization The type of decision(s) that they are charged with making The maturity of the investment The materiality of certain data elements to the decision The materiality of the decision to the organization