The use of abbreviations in answers can affect the usability of challenge questions.
A configurable traffic light system was designed and implemented to improve the usability of challenge questions.
Although, the use of a relaxed algorithm may enhance the usability of challenge questions, however, it can also increase the security risks.
Questionnaire item (3) asked for the usability of the questions in a real test on a 5-point scale, with 5 meaning "it can definitely be used in the actual test".
In certain situations and settings, such as AB usability testing, these types of questions can be quite valuable and informative.
Questions from our survey have been used in studies of US EDs and also have been used successfully in several other countries, ensuring usability and that the wording of questions was appropriate for diverse contexts [6, 9].
Finally, the children were asked four questions about trust and 17 questions about acceptance and usability of the system, in addition to five demographic questions.
Subsequently, the CAB provided feedback on wording and readability, question addition/deletion, assessed acceptability of questions and technology usability (see Technology section), and pilot tested questions before community-wide implementation.
See additional file 2: Usability Survey Questions and Groupings for a list of the usability survey questions and how they were grouped.
