Table 3 Guidance for assessing risk of performance bias for different study designs
Study design | Source of performance bias | Reported or suspected | Risk of performance bias |
|---|---|---|---|
BA | Confounding factor or time-related trend | Yes | High/Probably high |
No | Low/Probably low | ||
Unclear | Unclear | ||
CI and BACI | Confounding factor or contamination of study groups | Yes | High/Probably high |
No | Low/Probably low | ||
Unclear | Unclear | ||
Time-related trend | Yes or No | Low (N/A for CI) |