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Table 3 Critical appraisal criteria to assess individual studies in the full text stage

From: What are the effects of even-aged and uneven-aged forest management on boreal forest biodiversity in Fennoscandia and European Russia? A systematic review

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
  1. Studies that fulfilled any of the criteria in the category ‘high’ (e.g. effect modifiers not considered in an observational study with medium sample size) were considered ‘high risk’
  2. aSuitable sampling method refers to the use of methods that are known to work for the population in question based on published studies, e.g. flying insects are sampled by trapping or fogging, not by cutting branches
  3. bAppropriate methods refer to the use of statistical methods that consider data characteristics such as sample size and distribution. For example, non-parametric statistical tests are used for data that does not follow normal distribution