# Testing a New Structured Tool for Supporting Requirements' Formulation and Decomposition
## 5 Conclusions  
With a specific reference to systematic design procedures addressing physical products, the original aspects, the key findings, and the main lessons learned about the present contributions follow, and they will be further stressed in the residuals of this section:  
* A new tool has been introduced and tested to focus on the main products' functions and to subsequently support requirements' formulation by exploiting the advantages of both requirements' checklists and abstraction. * With a clear difference with respect to existing checklists, e.g., [9], and design methods, the tool disentangles itself from any specific meaning and interpretation of \"function\". In addition, thanks to such independence from the employed definition of function, the tool is a candidate for being used in different design disciplines and application fields. * A procedure to evaluate the metrics proposed in [28] has been fine-tuned, which has led to the possibility to achieve a considerable agreement between two expert coders. Markedly, from a methodological viewpoint, the procedure swivels on the ENV concept to assess validity and operationality, and on the individuation of stakeholders and lifecycle phases to evaluate completeness. * A previously unavailable performance benchmark has been determined in terms of the possible quality of the requirement formulation process in terms of the metrics proposed in [28]. * The results, and specifically the outcomes in terms of non-redundancy, have highlighted the need to separate requirements applicable to the whole design from those ascribable to specific functions. Previous design studies have failed to capture this aspect or, at least, to disclose it explicitly. Consequently, the handling of requirements that regard the design of a whole deserve specific research attention, with a particular reference to requirements' formulation or decomposition. * The results in terms of perceived effort concur to stress usability aspects beyond effectiveness when it comes to developing new design methods and tools. As mentioned, the main original element of the paper is represented by its targeting the problem of formulating useful and usable requirement lists, which has been abundantly overlooked hitherto. More specifically, the present study is concerned with investigating the effects of augmenting the level of structuredness in the use of standard checklists for design requirements, to be used in the context of engineering design of physical products. In this research domain, the paper presents the study of a candidate tool for supporting the formulation of comprehensive sets of engineering design requirements. The tool is constituted by a structured matrix, where the groups of columns represent the main functions of the desired product, and the rows are constituted by the checklist items, which are further subdivided into design wishes and demands. To test the matrix, a sample of thirty-six engineering students has been asked to formulate a set of requirements, by starting from an initial set of general product information. Eighteen students constituted the control group and they were asked to use the checklist [PERSON] and [PERSON] developed for conceptual design purposes. Differently, students in the analysis group were asked to use the proposed tool (implementing the same requirement checklist) by following the corresponding procedure. The outcomes from both groups have been assessed by means of well acknowledged metrics specifically developed for design requirements [28]. More specifically, the metrics adopted in this paper were Validity, Operationality, Non-redundancy, and Completeness. The outcomes of the experiment highlighted relevant problems for the proposed tool, especially in terms of the generation of redundant requirements. However, the likely reason of the problem has been identified and the means for an upgrade and more efficient version of the tool have been individuated.