Systematic Reviews
Data Coding
Levels of Coding
- Abstract screening
- Study eligibility screening
- Study content coding (full text coding)
Abstract Screening
- Is the study relevant based on the title and abstract
- Apply title/ abstract eligibility criteria
- If yes, retrieve full text
- If unclear, retrieve full text
- Exclude obviously irrelevant studies
- Include two trained raters working independently if possible
Study Content Coding (Full-Text Eligibility Screening)
- Develop an eligibility screening form based on the inclusion / exclusion criteria
- Complete for each study retrieved that is potentially eligible
- Include reasons for ineligible studies (for PRISMA reporting)
Data extraction form:
- Be consistent in the order and style you use to describe the information from each study
- Provide instructions, decision rules, and training on the use of the data extraction form
- Practice using the data extraction form
- Compare completed pilot forms
- Ensure that there is consistency in extracting data
- Ideally two researchers should independently perform data extraction
- Record any missing information as unclear or not described
- Makes it clear that the information was not included in the study rather than you forgot to extract it
Coding System
Data extraction
A coding system to extract data (i.e. study details) from each study needs to be developed prior to collecting data (i.e. searching)
Standardized data extraction provides consistency, thereby potentially reducing bias, improving validity and reliability
- Ensures that the same information is obtained (extracted) from each study
- Identifies key components of the research including interventions, subjects, and methods
- Should be developed early in the project
- Pilot the data extraction form with a sample of studies
- Keep track of revisions, corrections, amendments
- If possible, pilot the exporting, analysis, and outputs of the data extraction form
Data Extraction Resources
- Systematic Reviews:CRD's Guidance for Undertaking Reviews in Health Care.
Section 1.3.3 - pages 28 - 32 - Cochrane has developed templates that can be revised
Google: “data extraction form” cochrane (or other SR organization); "data extraction template" cochrane; "study eligibility checklist" cochrane; study selection checklist" cochrane
- Review published systematic reviews relevant to your research area
Request permission to adapt the data extraction form - Brown, Sharon A, Sandra LUpchurch, and Gayle Jacton. "A framework for developing a coding scheme for meta-analysis." Western Journal of Nursing Research 25.2 (2003):205-222.
- Brown, Sharon A, et al. "Managing complex research datasets using electronic tools: a meta-analysis exemplar." Computers, informatics, nursing 31.6 (2013):257-265.
Software for data extraction
- RevMan (Cochrane – can use free of charge for academic purposes)
- EPPI-Reviewer (one month free trial)
- JBI Sumari (subscription based)
- NVivo (UofC site license)
- Abstraktr
- Excel
- Access (database programs)
Elamin, Mohamed B, et al. "Choice of data extraction tools for systematic reviews depends on resources and review complexity." Journal of clinical epidemiology 62.5 (2009):506-510. This article reviews different data extraction tools and offers advice on which tool to use to extract data.
- Last Updated: Feb 16, 2024 1:58 PM
- URL: https://libguides.ucalgary.ca/guides/introSR
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