The Pugh Controlled Convergence method: model-based evaluation and implications for design theory

Abstract

This paper evaluates the Pugh Controlled Convergence method and its relationship to recent developments in design theory. Computer executable models are proposed simulating a team of people involved in iterated cycles of evaluation, ideation, and investigation. The models suggest that: (1) convergence of the set of design concepts is facilitated by the selection of a strong datum concept; (2) iterated use of an evaluation matrix can facilitate convergence of expert opinion, especially if used to plan investigations conducted between matrix runs; and (3) ideation stimulated by the Pugh matrices can provide large benefits both by improving the set of alternatives and by facilitating convergence. As a basis of comparison, alternatives to Pugh's methods were assessed such as using a single summary criterion or using a Borda count. These models suggest that Pugh's method, under a substantial range of assumptions, results in better design outcomes than those from these alternative procedures.

Research in engineering design: the role of mathematical theory and empirical evidence

“…Hazelrigg writes that ''the authors argue that the extant methods, Pugh included, obviously must have value since engineering has done so well ….'' To be precise, Frey et al (2009) do not claim it is ''obvious'', but we clarify here that there is a connection between the value of methods and their frequency in use.…”

“…The primary point of the paper ''The Pugh Controlled Convergence method: model-based evaluation and implications for design theory'' (Frey et al 2009) is that decision-making (analysis) and alternative generation (synthesis) have significant interactions that should be modeled if one is to evaluate design methodologies. The paper discusses a documented case study (Khan and Smith 1989), in which the chosen design concept was not among the initial set of design concepts being considered, but rather a new design that emerged after the engineers began the concept selection process.…”

“…The claims made in Frey et al (2009) are open to empirical testing by the design research community. One of our claims is that teams using Pugh Controlled Convergence in the concept design phase will, on average, produce better designs than teams implementing the suggested remedy in Saari (2006).…”

“…''The Pugh Controlled Convergence method'' (Frey et al 2009) states that ''there is no voting in Pugh method.'' Hazelrigg counters that voting is used both ''to obtain consensus on the relative merits'' and ''to aggregate the symbols'', and thus the Pugh method is invalidated based on Arrow's Impossibility Theorem.…”

“…Indeed, with its numerous points of critique of the paper ''The Pugh Controlled Convergence method'' (Frey et al 2009) stated so strongly, the letter demands a detailed rebuttal. We provide a response to the specific points discussed in the letter as well as the broader issues raised.…”