Bias domain | Question to Consider | Indicator | Score (1: Low Risk of Bias; 2: Medium Risk; 3: High risk) |
---|---|---|---|
Confounding bias | Did the study analysis adjust potential confounders appropriately? | Confounders adjusted | 1: Many confounders and unobserved confounding |
2: Some confounders (in particular mobility or socioeconomic variables) or unobserved confounders | |||
3: None or cannot tell | |||
Control of the population | Did the study control for population? | Population, age structure of the population | 1: Control and/or including population density |
2: Control only by including population density | |||
3: No control | |||
Control of the spatial and/or temporal dependence | Did the study control the spatial and/or temporal extra variability? | Spatial and temporal dependence | 1: Control |
2: Partial control (control of only one dependence, for example) | |||
3: No control | |||
Control of non-linearities | Did the study control for non-linearities? | Non-linearities (parametric or non-parametric) | 1: Control |
3: No control | |||
Measurement errors | What was the heterogeneity of indicators used in the study? | Measurement errors in the explanatory variables (exposure variables and covariates) | 1: Control |
2: Partial control (including lags, for example) | |||
3: No control | |||
Statistical model | Did the study use appropriate statistical model? | Statistical model | 1: Models for count data response variables |
2: Control of heteroscedasticity and rates as response variables | |||
3: Models with normally distributed errors and count data response variable; or no control of heteroscedasticity and rates as response variables | |||
Overall Study Rating | Strong (low risk of bias): one domain, at most, was rated as 3 | ||
Moderate: up to 2 domains were rated as 3 | |||
Weak (high risk of bias): ≥ 3 domains were rated as 3 |