Definition of Guideline-Based Metrics to Evaluate AAL Ecosystem’s Usability

Table 5

Shneiderman’s golden rules of parametrization [152–155].

Principle	Type	Parameters
3	AO	Providing a clear indication of the task’s completion rate; providing a progress bar for time-consuming operations; including the user in every interface screen information to identify his/her position within the interface navigation hierarchy (e.g., through the use of breadcrumbs).
4	AO	Providing a closure dialogue to give awareness to the end-user of the state in which the operation was concluded.
7	AO	Providing a dialogue to assert the user intentions upon the execution of a certain action.
7	SeO	Providing a clear indication of the current section and its hierarchical position within the interface structure using breadcrumbs; providing a global navigation menu.

Notes: 3: offer informative feedback; 4: design dialog to yield closure; 7: support internal locus of control.