Factor | Low | Medium | High |
---|---|---|---|
Study design | Experimental studies (includes also quasi-experimental studies) | Observational studies | Case studies (descriptive studies) |
Sampling | Large sample size Sampling method suitable for the population of interesta Properly conducted randomisation. Control and intervention areas matched | Small to medium sample size Sampling method suitable for the population of interesta Control and intervention 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 | Effect modifiers identified, and data collected on them | Effect modifiers identified and considered in relation to the results | Effect modifiers not identified or considered |
Data analysis methods | Methods appropriateb | Methods appropriateb | Methods not appropriateb |