Published on in Vol 7, No 2 (2020): Jul-Dec
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/18589, first published
.

1 School of Mathematical and Computer Sciences, Heriot-Watt University , Edinburgh , GB
2 School of Computing and Communications, The Open University , Milton Keynes , GB
3 Knowledge Media Institute, The Open University , Milton Keynes , GB
4 PJ Care Limited , Peterborough , GB