# The Human-Centredness Metric: Early Assessment of the Quality of Human-Centred Design Activities
## 2 Materials and Methods
### Evaluating Product Concepts
#### 2.2.5 Complete Human-Centredness Metric (HCM)  
In accordance with our objective, we primarily need lists of criteria from which a cumulative score for the evaluation of human-centredness can be derived. In the case of empathic methods as well as walkthrough methods, or process-based methods in general, which also include model-based approaches, this is more difficult to implement. For the derivation of a metric for the early measurement of human-centred goal setting, we therefore use the guidelines presented above and, if possible, give priority to those whose phrasing can be used for general product design as well as for early development phases. In summary, we derive 21 criteria for the usability aspect, primarily from [33; 34]. Based on the best practices from [43] as well as the criteria for evaluating visual aesthetics from [45], we obtain another 12 criteria for user experience. However, we do not list those criteria from [43] that are covered by the usability criteria, as well as those from [43; 45] that are not suitable to be used in the early development phases, such as the evaluation of the colour style. For accessibility, we derive a total of eight criteria from [50; 51; 52]. For the avoidance of use-related damage, we obtain 13 criteria that can be anticipated at early development from the machinery directive [56]. Usability (21)  
1. Interaction elements are simple and clear
2. Minimal number of actions required to complete task
3. Operations are effective, i.e., require low effort
4. Operations are efficient, i.e., require little time
5. Interaction elements are easily reachable when needed
6. Direct feedback about system status and operations
7. Intuitive perceptibility of functions and interaction elements
8. Intuitive understandability of functions and interaction elements
9. Helpful information is available when needed
10. Users have control over all functions
11. Users have the feeling of direct manipulation
12. Functions are easy to control
13. Users can correct errors when they occur
14. Design prevents errors by users to a large extent
15. Each interaction element is unique in terms of its use
16. Effort required to learn the operation is low
17. Operation is easy to memorise
18. Operation can be adapted to the needs of the user
19. Operation is internally consistent, i.e., design for elements with similar function is also similar
20. Operation is familiar from other areas to users
21. Operation and interaction elements are predictable for the userUser Experience (12)  
1. Users do not get the feeling of incompetence in operation
2. Continuous work is possible/no forced interruptions
3. Operation creates a feeling of security/prevents feeling of insecurity
4. Design fulfils expected fundamental functions
5. Design has recognisable technological advance
6. Product form fits the context of use
7. Total number of visible individual parts is rather small
8. The system is simple and small, redundant functions are reduced as much as possible
9. Elements and functions are visually merged or organised into sets
10. Form and shape complexity, i.e., the total number of lines and curves, the change in their direction, and the amount and type of combinations of shapes that occur, is small
11. Proportions follow a harmonic design; dimensions differ for purely ergonomic and functional aspects
12. Product form follows a cohesive style characterised by unity, contrast, or balance  
Accessibility (8)  
1. Interaction elements can be detected by means of two sensory capabilities
2. Operating target can be reached via two independent paths
3. Interaction elements are intuitively recognisable
4. Elements and functions are clearly and noticeably labelled
5. Interaction elements are accessible with reduced mobility
6. Interaction elements can be operated with little physical strength
7. Working speed is reasonable and/or can be adjusted to the user
8. System uses a language that is easy to understand  
Avoidance of Use-Related Damage (13)  
1. The shape does not lead to mechanical hazards
2.