A Trade Study is a study that identifies a preferred solution among a list of qualified solutions. The trade study will examine these solutions against criteria such as; cost, schedule, performance, weight, system configuration, complexity, the use of Commercial off-the-Shelf (COTS), and many others. Trade Studies are performed throughout an acquisition program from concept development thru system design. In systems engineering, they’re primarily used to determine operational and system level requirements.
Trade studies are used in support of decision making throughout the life cycle of a program. Trade studies are conducted among operational capabilities, functional, and performance requirements, design alternatives and their related manufacturing, testing, and support processes; program schedule; and life-cycle cost to systematically examine alternatives. Once alternatives have been identified, a trade study team applies a set of decision criteria to analyze the alternatives. These criteria are ‘traded’ to determine which alternative is optimal and to be recommended.
Most trade studies are not strictly formal or informal; usually they fall somewhere in between these two extremes. As a general rule, formal trade studies are indicated for high-value, high-risk or other high-impact decisions. Not all trade studies should follow the full rigor of a formal process, but should be tailored to the specific circumstances of the program such as: 
- Likelihood or severity of programmatic risk,
- Objectivity and quantitative data used,
- Details in available data, and
- Time, effort and money needed to conduct the trade study.
Trade Studies support the following activities:
- Alternative Architecture Analysis
- Requirements Analysis
- System Analysis and Control
- Functional Analysis and Allocation
- Design Synthesis
- Selected Preferred Alternatives
- Measures of Effectiveness
AcqLinks and References:
-  Defense Acquisition Guidebook (DAG) – Chapter 4
- NAS System Engineering Manual – Trade Studies – Section 4.6
- White Paper: Trade Studies with Uncertain Information, INCOSE – July 2006
- SMC Systems Engineering Primer & Handbook
- White Paper: Standard Approach to Trade Studies: A Process Improvement Model that Enables Systems Engineers to Provide Information to the Project Manager by Going Beyond the Summary Matrix, INCOSE – Nov 2004