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Table 1 Coding scheme for primary studies (adapted from Thomas et al., 2008)

From: Synthesising evidence for equity impacts of population-based physical activity interventions: a pilot study

Design feature

Definition

Coding

a. Suitability of study design

The height of the bar represents the level of suitability in the design of the evaluation

Level 1 - The study involved measurements of exposure and outcome at a single point in time

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Level 2 - The study design involved single 'before' and 'after' measurements with no concurrent comparison group

Level 3 - The study design included at least two 'before' measurements and at least two 'after' measurements but no concurrent comparison group

Level 4 - The study design included concurrent comparison groups AND prospective measurement of exposure and outcome

b. Methodological quality criteria

The annotated number represents an overall score for methodological execution of the study. Studies are scored on a scale between 0–6, dependent on how many of the methodological features are achieved in each study

Representativeness: Were the study samples randomly recruited from the study population with a response rate of at least 60% OR were they otherwise shown to be representative of the study population?

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Randomisation: Were participants, groups or areas randomly allocated to receive the intervention or control condition?

Comparability: Were the baseline characteristics of the comparison groups comparable OR if there were important differences in potential confounders were these appropriately adjusted for in the analysis? If there was no comparison group this criterion could not be met

Credibility of data collection instruments: Were data collection tools shown to be credible, e.g. shown to be valid and reliable in published research, OR in a pilot study, OR taken from a published national survey, OR recognized as an acceptable measure (such as a biochemical measures of smoking)?

Attrition rate: Were outcomes studied in a panel of respondents with an attrition rate of less than 30% OR were results based on a cross-sectional design with at least 200 participants included in analysis in each wave?

Attributability to intervention: Is it reasonably likely that the observed effects were attributable to the intervention under investigation? This criterion could not be met if there was evidence of contamination of a control

c. Physical activity outcome metrics

The tone of the bars indicates what type of outcome metric was used in each study

White = Direct observation

Grey = Self-reported measures

Black = Objective measures