Ulrich 2007.

Methods	Allocation: randomised. Blindness: single ‐ assessor blinded; assessors unaware of study aim; success of blinding verified by letting assessors guess what the study aim was; none were aware that the study aim involved music therapy. Duration: 4.8 weeks. Design: parallel group.
Participants	Diagnosis: schizophrenia or related psychoses (27 of 37 had F20 in ICD‐10). History: unknown. N = 37. Age: mean 38 years, range 22 to 58. Sex: 20 M, 17 F. Setting: inpatients.
Interventions	1. Active group music therapy (focusing on musical processes and discussion of patients' problems), 60 to 105 minutes per session, on average 7.5 sessions. N = 21. 2. Standard care (medication, "other" activities ‐ no detailed description given). N = 16.
Outcomes	Mental state, negative symptoms: Scale for the Assessment of Negative Symptoms (SANS; Andreasen 1982). Quality of life, mental health: Skalen zur psychischen Gesundheit [scales about mental health] (SPG; Tönnies 1996). Unable to use ‐ unvalidated subscales of published scale: Gießentest.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A dice was thrown.
Allocation concealment (selection bias)	Unclear risk	No details given.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Personnel and patients were blinded to the fact that research of music therapy was the study aim.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Assessors were blinded to the research aim. Blinding was tested successfully at the end of the study. No one indicated that the aim of the study was testing the effectiveness of music therapy.
Incomplete outcome data (attrition bias) All outcomes	Low risk	People leaving early were reported. Intention‐to‐treat analysis was used: Participants whose diagnosis was changed after inclusion in the study were not excluded.
Selective reporting (reporting bias)	Unclear risk	No study protocol available. All outcome measures described in the study were considered in the analysis.
Other bias	Low risk	Adequate music therapy method: yes. Adequate music therapy training: yes (based on a general statement: 'qualified music therapists' and a reference in the article). No financial, personal or other interests producing bias detected.