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RoB 2 Tool: Risk of Bias in Randomized Trials

Record Cochrane RoB 2 judgements for each trial, get the overall risk of bias suggested by the RoB 2 rules, and download publication-ready traffic light and summary plots.

FreeNo account neededYour data stays in your browser

Domains and how to use them
  1. D1: Bias arising from the randomization processRandom sequence, concealed allocation, and baseline balance between groups.
  2. D2: Bias due to deviations from intended interventionsAwareness of assignment, departures from the protocol, and whether the analysis suits the effect of interest.
  3. D3: Bias due to missing outcome dataHow much outcome data is missing and whether missingness could depend on the true outcome.
  4. D4: Bias in measurement of the outcomeSuitability of the measurement method, differences between groups, and assessor awareness.
  5. D5: Bias in selection of the reported resultWhether the result was chosen from several outcome measurements or analyses.

Answer the signalling questions in the official tool, then record your judgements here: RoB 2 guidance and templates (riskofbias.info).

StudyD1D2D3D4D5Overall

Your entries are saved in this browser only. Nothing is uploaded.

Low only if all domains are low; high if any domain is high. You can also judge a trial high overall when several domains raise some concerns that together substantially lower confidence in the result (use the override).

Summary plot

Traffic light plot

StudyD1D2D3D4D5OverallExample trial 1++++++Example trial 2−++−+−Example trial 3+×−++×Example trial 4++−+−−Example trial 5×−+++×D1: Bias arising from the randomization processD2: Bias due to deviations from intended interventionsD3: Bias due to missing outcome dataD4: Bias in measurement of the outcomeD5: Bias in selection of the reported result+Low risk−Some concerns×High risk

Summary plot

D1. Bias arising from the randomization process60%20%20%D2. Bias due to deviations from intended interventions60%20%20%D3. Bias due to missing outcome data60%40%D4. Bias in measurement of the outcome80%20%D5. Bias in selection of the reported result80%20%Overall20%40%40%0%25%50%75%100%Low riskSome concernsHigh risk
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How to Use the RoB 2 Tool (Risk of Bias 2)

  1. 1

    Answer the official signalling questions

    Use the linked tool document for each study or result.

  2. 2

    Record your judgements

    One row per study, one column per domain; the overall judgement is suggested for you.

  3. 3

    Download the figures

    Traffic light and summary plots as PNG or SVG, plus a CSV of your table.

What is the RoB 2 tool?

RoB 2 is the Cochrane tool for assessing risk of bias in randomized trials. It covers five domains: the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result.

Each domain is judged as low risk, some concerns or high risk, using signalling questions set out in the official guidance. The assessment applies to a specific result, so the same trial can be judged differently for different outcomes.

This tool records your judgements and draws the figures; it does not replace the signalling questions, which you should answer using the official RoB 2 guidance.

How it is calculated

Sources

RoB 2 Tool (Risk of Bias 2): FAQ

What are the five domains of RoB 2?

Bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome, and bias in selection of the reported result.

How is the overall RoB 2 judgement made?

Low if every domain is low; some concerns if any domain has some concerns and none is high; high if any domain is high, or if several domains with some concerns substantially lower confidence in the result.

Can I make a traffic light plot without R?

Yes. Enter your judgements here and download the traffic light and summary plots as PNG or SVG.

Are my assessments stored anywhere?

Only in your own browser. Download the CSV to keep a copy or share it with your co-reviewer.

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