{{No footnotes, date=September 2010 A trade study or

trade-off A trade-off (or tradeoff) is a situational decision that involves diminishing or losing one quality, quantity, or property of a set or design in return for gains in other aspects. In simple terms, a tradeoff is where one thing increases, and anot ...

study, also known as a figure of merit analysis or a factor of merit analysis, is the activity of a

multidisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of multiple academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fields like sociology, anthropology, psychology, ec ...

team to identify the most balanced technical solutions among a set of proposed viable solutions (FAA 2006). These viable solutions are judged by their satisfaction of a series of measures or cost functions. These measures describe the desirable characteristics of a solution. They may be conflicting or even

mutually exclusive In logic and probability theory, two events (or propositions) are mutually exclusive or disjoint if they cannot both occur at the same time. A clear example is the set of outcomes of a single coin toss, which can result in either heads or tails ...

. Trade studies are commonly used in the design of

aerospace Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...

and automotive vehicles and the

software Software is a set of computer programs and associated software documentation, documentation and data (computing), data. This is in contrast to Computer hardware, hardware, from which the system is built and which actually performs the work. ...

selection process (Phillips et al. 2002) to find the configuration that best meets conflicting performance requirements. The measures are dependent on variables that characterize the different potential solutions. If the system can be characterized by a set of equations, one can write the definition of the trade study problem as: Find the set of variables, x_i, that give the best overall satisfaction to the measures: * T₁ = f₁(x₁, x₂, x₃.....) * T₂ = f₂(x₁, x₂, x₃.....) * T₃ = f₃(x₁, x₂, x₃.....) * * T_N = f_N(x₁, x₂, x₃.....) Where T_j is a target value and f(...) denotes some

functional Functional may refer to: * Movements in architecture: ** Functionalism (architecture) ** Form follows function * Functional group, combination of atoms within molecules * Medical conditions without currently visible organic basis: ** Functional s ...

relationship among the variables. Further, the equality between the target and the function may be a richer relationship, as will be developed below. If the equations are

linear Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear ...

, as in the production volume example used as a starting point below, then this problem is solvable using

linear programming Linear programming (LP), also called linear optimization, is a method to achieve the best outcome (such as maximum profit or lowest cost) in a mathematical model whose requirements are represented by linear relationships. Linear programming is ...

techniques. Generally, one or more of the targets is not fixed at a specific value, and it is desired to make these T values as large or small as possible. These are generally referred to as cost functions, and the other measures are treated as

constraint Constraint may refer to: * Constraint (computer-aided design), a demarcation of geometrical characteristics between two or more entities or solid modeling bodies * Constraint (mathematics), a condition of an optimization problem that the solution ...

s. If the situation was as described above, formal optimization or linear programming methods would work totally. However, in practice, needed information is: * Uncertain * Evolving - new information is being developed that affects the trades * Both

qualitative Qualitative descriptions or distinctions are based on some quality or characteristic rather than on some quantity or measured value. Qualitative may also refer to: *Qualitative property, a property that can be observed but not measured numericall ...

and

quantitative Quantitative may refer to: * Quantitative research, scientific investigation of quantitative properties * Quantitative analysis (disambiguation) * Quantitative verse, a metrical system in poetry * Statistics, also known as quantitative analysis ...

* Comes from conflicting sources - in

systems engineering Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking ...

, many people have some of the information needed; no one person has it all. * The best choice comes from a team, building a shared

mental model A mental model is an explanation of someone's thought process about how something works in the real world. It is a representation of the surrounding world, the relationships between its various parts and a person's intuitive perception about thei ...

of the situation.

References

* FAA, System Engineering Manual Version 3.1, Section 4.6, Trade Studies, Federal Aviation Administration, 2006

* Phillips, B. C. and S.M. Polen, Add Decision Analysis to Your COTS Selection Process, Crosstalk, April 2002 * Ullman D.G. and B.P. Spiegel, Trade Studies with Uncertain Information, Sixteenth Annual International Symposium of the International Council On Systems Engineering (INCOSE), July 2006

Decision analysis

See also

References