Factor | Low | Medium | High |
---|---|---|---|
Study design | Experimental studies (includes also quasi-experimental studies) | Observational studies (intervention is not under the control of the researcher) | Case studies (descriptive study of a particular case) |
Sampling | Large sample size relative to outcome measure and species in question (high confidence that replication is appropriate and representative) Sampling method suitable for the population of interesta Randomisation of the study areas accounts for spatial heterogeneity Random sampling of study subjects Control and exposure areas matched based on their ecological characteristics | Small to medium sample size relative to outcome measure and species in question (medium level of confidence that replication is appropriate and representative) Sampling method suitable for the population of interesta Control and exposure areas comparable based on their ecological characteristics | Sampling method not suitable for collecting data on the population of interesta |
Accounting for heterogeneity and potential effect modifiers | Potential biologically important effect modifiers that could influence the study findings identified, and data collected on them. The context in which the study took place clear | Potential biologically important effect modifiers that could influence the study findings identified and considered in relation to the results. The context in which the study took place clear even when there was no direct data collection | Effect modifiers not identified or considered. The context of the study is unclear |
Data analysis methods | Methods appropriateb | Methods appropriateb | Methods not appropriateb |