Table 3 Studies internal validity critical appraisal tool
Risk of biases | Question | Low | High | Unclear |
|---|---|---|---|---|
Confounding factors | Are there potential confounding factors influencing the exposure/intervention or outcome? (e.g. different ecosystems between sites, additional uncontrolled exposures such as light, chemical or noise pollution) | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Post-exposure/intervention selection | Are experimental sites/groups randomly and/or systematically selected and exchangeability can be assumed after the exposure/intervention? | Yes or seemingly yes | No or seemingly no | Unknown or unclear |
Attrition | Were there any differences in missing data between experimental sites/groups during the study or the analysis? | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Misclassified comparison (only observational) | Are exposure/intervention and comparator groups sufficiently well defined? | Yes or seemingly yes | No or seemingly no | Unknown or unclear |
Performance (only experimental) | Was the exposure/intervention altered during the experiment and thus differed between experimental sites/groups? | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Detection | Are they differences in how outcomes were measured between experimental groups/sites? | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Outcome reporting | Are reported findings selectively disclosed? | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Outcome assessment | Were assumptions for the applied statistical analyses violated? (e.g. normality, homoscedasticity) | No or seemingly no | Yes or seemingly yes | Unknown or unclear |
Exposure | Are real (not simulated) photovoltaic or solar thermal panels used? | Yes or seemingly yes | No or seemingly no | Unknown or unclear |