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Table 2 Draft quality coding tool

From: What is the evidence that invasive species are a significant contributor to the decline or loss of threatened species? A systematic review map

Generic data quality features Specific data quality features Quality element Quality score
Internal validity of study N/A Clear aims 2
Treatment and control groups similar at start of trial (low heterogeneity between locations, size of exp. areas, soil type, shading, plant types etc.) 2
Outcomes measured accurately and reliably 2
Control of confounding variables 2
Replications of study 2
Study Design N/A Randomised block design time series (pre-intervention data/observations) 80
Non-randomised block design time series 60
Historical dataset e.g. >10 years (not from current experimental observation) 50
Data without comparator 30
Descriptive, field observations 20
Expert opinion 10
Measurement of outcomes Quantitative measurements of intervention Population size, range, density, fecundity–pop. counts/mark-recapture/nest counts/dropping counts 10
Qualitative/descriptive observations of intervention (e.g. vague estimate of time since introduction) Population size, range, density, fecundity 5