The online trial ran from July 2021 to January 2022 and was a random sample of people who had completed the telephone survey, stratified by local authority.
Cynhaliwyd y treial ar-lein rhwng mis Gorffennaf 2021 a mis Ionawr 2022 ac roedd yn sampl ar hap o bobl a oedd wedi cwblhau'r arolwg ffôn, wedi'i haenu gan yr awdurdod lleol.