Abstract
Many TRIZ critics (but also advocates) challenge its capability to individuate appropriate instruments for specific problems. Although each TRIZ user tends to prefer certain tools over others, Inventive Principles represent the most popular technique according to recent studies. Consequently, a more appropriate guidance to select the most promising ones for a given problem would result in a clear advantage for designers and supposedly for TRIZ popularity. The Contradiction Matrix is classically introduced to support this process, but its reliability is often questioned. In this framework, the authors have analysed a sample of problems solved by means of TRIZ and described in TRIZ-related literature. This choice was dictated by the need to pay attention to case studies really faced with TRIZ instead of being reconstructed from other examples, e.g. patents. The performed analysis has included 42 case studies from acknowledged TRIZ books and sources. Unfortunately, literature about problems solved with TRIZ is highly dispersed and the creation of a greater sample would have required considerable efforts. By the way, the authors believe that such a situation hinders the communication of TRIZ benefits. The analysis has led to the conclusions that follow. The Contradiction Matrix would have supported the determination of the described solutions in very few cases, namely 8, which confirms its limited reliability. A small number of Inventive Principles is capable of addressing the majority of the illustrated solutions; for instance, four of them are sufficient to solve almost 60% of the presented problems. Additional criteria have been used to classify conflicting parameters (more specifically a characterization in terms of Useful Functions, Undesired Effects and Resources), but their relationship with employed Inventive Principles seems quite random. The paper wills to open up a discussion about this presumable randomness of Inventive Principles and the possible measures to tackle the problem.