For a formative evaluation, a sample size as small as five is considered sufficient to highlight usability issues of the system, and almost 100%% of the usability problems can be found using 14 participants [ 23, 24].
In fact, the products available on the market have not yet reached a sufficient level of usability, thus discouraging most radiologists from using them.
While these devices are increasingly being used to cover health needs, there are not sufficient studies addressing usability of smartphone user interfaces for older adults.
Consequently, being open does not seem to be sufficient in terms of usability, even if a deep modelling understanding exists.
Finally, for more usability of adaptation, sufficient accuracy of information and functionalities of application must be achieved.
The evaluation shows that the framework has a complete set of criteria with a sufficient level of coherence, but its usability and efficiency is argued differently.
Quality indicators could be helpful to quickly determine which attributes still require panel training, when panel training has been done in a sufficient manner and to determine the usability of the final results.
In keeping with usability testing recommendations, our sample was sufficient to identify the large majority of usability issues [ 54].
There are many potential reasons for this: even though many CME-websites exist, the usability of some sites is not sufficient.
The sample size should be sufficient, as research has shown that up to 80% of usability issues can be identified with 5 to 8 participants [ 33].
