Bai 2005.

Methods	Allocation: random, no further details. Blindness: single, no further details. Duration: 24 weeks. Design: parallel.
Participants	Diagnosis: chronic schizophrenia. N=80. Age: mean=50.2 years, range not described. Sex: 39M, 41F. Setting: not described. History: duration illness not described, age of onset not described. Excluded: not described.
Interventions	1. Amisulpride: dose range not described, mean dose not described, fixed/flexible dose not described. N=40. 2. Olanzapine: dose range not described, mean dose not described, fixed/flexible dose not described. N=40.
Outcomes	Leaving the study early: any reason. Cognitive functioning: Wisconsin card sorting test. Unable to use ‐ Mental state: BPRS change (no data). Adverse effects: BAS, SAS, UKU (no data).
Notes	There are control groups without further details provided.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Random, no further details.
Allocation concealment (selection bias)	Unclear risk	No further details.
Blinding (performance bias and detection bias) Objective outcomes	Low risk	Objective outcomes such as laboratory measures or death are unlikely to have been much affected by problems of blinding.
Blinding (performance bias and detection bias) Subjective outcomes	Unclear risk	Single, no further details. 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 (attrition bias)	Low risk	The rate of leaving the study early was only 5% and data on reasons for leaving early were provided. All data were analysed on an intent to treat basis with the last‐observation‐carried‐forward method. This method is not perfect, but due to the very low attrition the risk of bias was low.
Selective reporting (reporting bias)	High risk	The study is only available as an abstract. Data on BPRS and EPS scales were not available.
Other bias	Unclear risk	Insufficient data to judge on baseline imbalance or industry sponsoring.