An analytical (and, sometimes experimental) process used to select a “best” or “preferred” option or course of action from among several candidates by ranking them with respect to application-specific criteria.
A good trade study should be organized as an optimization problem (which may be either linear or non-linear) seeking to maximize (or minimize) an Objective Function with regard to Constraints (which may be either continuous or categorical in nature). The Objective Function should be formulated as a Utility Function (as the term is used in Economics) from the dot product of the non-dimensionalized criteria values and the criteria weights, where the weight vector sums to exactly one (1).
In this formulation, the weight vector is, therefore, the first eigenvector of the preferences matrix formed from the criteria. See the Analytic Hierarchy Process (AHP, a.k.a. “the Saaty Method”), but replace that portion of the AHP that attempts to rank the options according to belief with technical analysis of the options relative to the criteria and constraints. Note that, in this formulation, the criteria must be “orthogonal”: combinations that can be formulated in terms of each other are disbarred from this exercise, and must be replaced with a surrogate criterion and (perhaps) one or more constraint relationships.
Furthermore, the measures (quantities) of the criteria must be explicit and traceable to measures of requirement (as found in the requirements allocated to the CI or in the governing SoW for which the trade study is being conducted). The criteria should always include cost in most (possibly all) of its forms.
The exercise can be (and should be) conducted as a double-blind experiment iff determination of the criteria weights is executed by an independent “agent” having no visibility into the technical analysis, and held sub rosa until all the analytical results are available.
Used properly, the trade study concept is a powerful technique for bringing order from the chaos of uncertain decision-making. More often (unfortunately), the concept is an outstanding cover for the incorporation of wishful thinking and fondly-held belief by hijacking the criteria weights when nobody’s looking.