Published on in Vol 7 , No 4 (2019) :Oct-Dec
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/15980, first published
.

1 School of Computer Science & Informatics, Cardiff University, Cardiff, GB
2 School of Psychology, Cardiff University, Cardiff, GB
3 School of Mathematics, Cardiff University, Cardiff, GB