Methods	Allocation: random, no further details. Blindness: single, rater-blinded. Duration: 12 weeks. Design: parallel. Location: single centre. Country: Israel.
Participants	Diagnosis: (DSM-IV) schizophrenia, PANSS negative subscore of more than 15, SANS total score more than 60. N=40. Age: 21-64 years (mean olanzapine=36.2 years, mean quetiapine=38.3 years). Sex: 32 M, 8 F. History: duration ill mean olanzapine=13.3 years, mean quetiapine=15.9 years, age at onset not reported. Setting: inpatient.
Interventions	Olanzapine: flexible dose. Allowed dose range: 5-20 mg/day. Mean dose: 16.0 mg/day. N=21. Quetiapine: flexible dose. Allowed dose range: 200-800 mg/day. Mean dose: 637.2 mg/day. N=19
Outcomes	Leaving the study early: any reason, adverse events, inefficacy. Mental State: PANSS total score, SANS. Adverse effects: open interviews, cardiac effects (ECG), EPS (akathisia, parkinsonism, use of antiparkinson medication, SAS, AIMS, BAS), sedation, insomnia, abdominal pain, fever, rhinitis, conjunctivitis, seizures, weight gain Unable to use - Mental State - PANSS total score (median change). Negative Symptoms - SANS (median change). EPS scales (no data). Cardiac effects (no data).
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Random, no further details.
Allocation concealment?	Unclear risk	No further details.
Blinding? Objective outcomes	Low risk	Objective outcomes such as laboratory measures or death are unlikely to have been much affected by problems of blinding
Blinding? Subjective outcomes	Unclear risk	Single, rater-blind. Whether blinding was successful has not been examined, but both compounds differ quite substantially in side-effects. This can be a problem for blinding
Incomplete outcome data addressed? All outcomes	Low risk	The attrition rate was quite low (12%). The last-observation-carried-forward method was used to account for people leaving the study early. It assumes that a participant who discontinued the study would not have had a change of his condition if he had remained in the study. This assumption can obviously be wrong. For the reason of low attrition the risk of bias can be considered as low
Free of selective reporting?	High risk	Efficacy data (PANSS, SANS) were only presented as median change. There were no data on EPS and cardiac effects
Free of other bias?	High risk	The study was sponsored by the manufacturer of quetiapine.