# The Human-Centredness Metric: Early Assessment of the Quality of Human-Centred Design Activities
## 2 Materials and Methods
### Evaluating Product Concepts  
Before introducing our approach to measuring human-centredness, a brief explanation of the general types of methods that can be used to evaluate product concepts shall be presented here. Figure 2 illustrates classes of evaluation methods categorised along the dimensions \"analytical vs. empirical\" and \"formative vs. summative\". In this context, \"empirical\" refers to the evaluation of product concepts by potential users, as opposed to analytical evaluation, wherein evaluations are performed by experts, i.e., researchers or designers. Although it is theoretically possible to conduct all analytical evaluation methods of Figure 2 also together with potential end users, this requires certain technical and procedural know-how on the side of the participants in the method, which is usually either not widely distributed among the user group or would lead to a major restriction in the selection of the participants. The latter, however, also jeopardises the representative selection of participants of user involvement and cannot be recommended without restrictions. [PERSON] et al. [27] attempted something similar in their experiment, but included also only people with an engineering design background. Figure 1: Deriving a working definition [8; 17; 28]. Figure 2: Classes of evaluation methods and differentiating dimensions. Formative and summative methods differ in the point in the development process at which the evaluation can be carried out. However, as in the case of the distinction between analytical and empirical, this boundary is not a sharp line and has a certain intersection. Summative methods form a final judgment on an (almost) finished product. Without elaborated prototypes or established products on the market with a larger user community, summative approaches can hardly be performed. Formative procedures, on the other hand, allow the measurement of goal achievement in the ongoing development process at different stages of design. For example, interviews and different variations of them can be integrated at different points in the development process. They could be used in the form of the thinking aloud technique for a more formative evaluation already during development. For the purpose of a summative evaluation, interviews could be used in the form of asking users about past product interactions, as well as about any operating problems they encountered or their satisfaction with the product in retrospect. Interviews, as a class of methods, can therefore be assigned to both formative and summative approaches, but are always to be conducted empirically (Figure 2). In alignment with our research inquiry, our objective is to establish quantifiable metrics for human-centredness that can be applied on the resulting product concepts. This approach aims to provide an immediate assessment, shortly after a human-centred method has been implemented, rather than relying on the documentation of the activities that have led to these product concepts over a longer period of time. Thus, we need a formative evaluation method that can be applied to the very early stages of development, long before physical prototypes and preferably even before detailed 3D models exist. Although there are formative approaches on the side of empirical methods (Figure 2), they still need at least basic functional prototypes for execution. We place our focus on the search for analytical methods that do not depend on the involvement of users, but still provide information about the context of use. Moreover, the metric that we derive should be applicable both to researchers specialising in human-centredness and to product designers themselves, facilitating prompt and early assessments of the efficacy of human-centred methodologies, as well as the identification of any vulnerabilities within the product concept. This means that the assessment, on the other hand, may also demand a certain level of know-how on the side of the method user and can be expert-based.