Clark 1998

Methods	RCT (crossover 2 weeks + 2 weeks). No information on data collection period reported.
Participants	Country: USA. N = 18 (14 female, 4 male). Mean age: 82 (range 55 to 95), residents in a nursing home with Alzheimer‐type dementia. Inclusion criteria presence of dementia and a history of aggressive behaviour exhibited during care giving routines. Presence of dementia was assessed with the MMSE (Mean = 10, range 0 to 22); most residents had severe dementia. Exclusion criteria: Uncorrected hearing impairment. Absence of family member who could provide knowledge of a potential participant's music preferences.
Interventions	(1) Favourite music during bathing (receptive intervention). (2) No music during bathing. Following a 2‐week (10‐sessions) observation period, conditions were reversed. A total of 20 sessions (bathing episodes; 10 control, 10 experimental) were observed over a period of approximately 4 weeks. Probably the intervention was provided for all bathing episodes and all were observed.
Outcomes	Behaviour: frequency of aggressive behaviours (no specific measure was used, but counts and mean counts across specific behaviours).
Notes	No information about funding available. Note that the study also included younger people with dementia.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "After being enrolled in the study, participants were randomly scheduled for observation during bath time under either a control (no music) condition or an experimental condition." No further information is provided on randomization.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible to blind the convener and participants.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information provided.
Selective reporting (reporting bias)	Unclear risk	The study protocol is not available.
Other bias	High risk	Questionable outcome measure and distribution. The authors report in the article on the effects of the extreme intra‐subject and inter‐subject variability characteristic of this population in this study. Quote: "For example, one subject was responsible for 408 and 84 occurrences of yelling behaviour in the no music and music conditions, respectively". Therefore, highly skewed distributions (the observation hardly occurred) causing imprecision.