Bah humbug! Association between sending Christmas cards to trial participants and trial retention : randomised study within a trial conducted simultaneously across eight host trials
Citation
Coleman , E , Arundel , C , Clark , L , Doherty , L , Gillies , K , Hewitt , C A , Innes , K , Parker , A , Torgerson , D & Treweek , S 2021 , ' Bah humbug! Association between sending Christmas cards to trial participants and trial retention : randomised study within a trial conducted simultaneously across eight host trials ' , BMJ , vol. 375 , e067742 . https://doi.org/10.1136/bmj-2021-067742