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Table 4 Frequency of risk of bias judgements in each bias domain across included outcomes

From: The effect of changing the built environment on physical activity: a quantitative review of the risk of bias in natural experiments

Risk of bias judgement Pre-intervention At-intervention Post-intervention Overall bias
Bias due to confounding Bias in selection of participants into the study Bias in measurement of interventions Bias due to departures from intended interventions Bias due to missing data Bias in measurement of outcomes Bias in selection of the reported result
Low - - 6 8 8 1 - -
Moderate - 7 4 3 4 - - -
Serious 14 7 5 4 2 11 15 3
Critical 1 1 - - - 3 - 12
No information - - - - 1 - - -