Bias Assessment Tool
A bias assessment tool is a standardized instrument used to evaluate the bias risk in individual studies included in a systematic review or meta-analysis.
These tools help reviewers judge the internal validity of studies and assess how much trust can be placed in their results.
Purpose
- Identify potential sources of systematic error
- Grade the quality and credibility of included studies
- Support transparent, evidence-based conclusions
Commonly Used Tools
| Tool | Target Study Design | Description |
|---|---|---|
| Cochrane RoB 1 | Randomized Controlled Trials (RCTs) | Assesses seven domains of bias (e.g., selection, performance, detection) |
| Cochrane RoB 2 | RCTs (updated version) | Focuses on bias at the outcome level; structured judgments with signalling questions |
| ROBINS-I | Non-randomized studies | Evaluates bias across seven domains before and after intervention |
| Newcastle-Ottawa Scale | Observational studies | Assesses selection, comparability, and outcome/exposure |
| AMSTAR 2 | Systematic reviews | Appraisal of reviews' methodological quality, especially in healthcare |