Hi:

Basically, for business systems, there are two main types of requirements that a BA deals with:  Behavioral requirements and data requirements.   (There is also things like performance requirements, but I am putting  those other things to the side here.)

Requirements analysis is determining, as necessary, both behavioral requirements and data requirements.   Structured analysis largely consists of specific techniques to discover system - both manual and automated systems - behavioral and data requirements.  CAUTION:  Do not be lead into confusion by those who think that  sturctured analysis is only for automated systems.  That is a VERY popular notion - even within the BABOK - that is wrong.

Object-Oriented Analysis (OOA) also largely consists of specific techniques to discover system behaviroal and data requirements.   Some say that OOA can be used for manual as well as automated systems.   But most say OOA is only for automated systems because it's techniques  refer to things like "messages", "packages", and "objects" which are largely techo weenie terms.

What is the main dfference between structured analysis and OOA?  Behavorial requirements analysis drives data requirements analysis, and the real task at hand in behavioral requirements analysis is not understanding standalone requirements but the essential  interrelationships between the behavioral requirements.  These essential interrelationships are inputs and outputs - typically data flows.  Only structured analysis techniques, specifically data flow diagrams, address discovery of data flows.  OOA techniques do not.

Soooo, I suggest using structured requirements analysis for higher level business modeling on larger scale efforts, and using OOA for smaller scale efforts where the objective is to jump into implementation as soon as possible.

Tony

Answer:  For behavioral requirements discovery (which drives data requirements discovery),