Blog
22/4/2025
As awareness grows about the impact of our environments on health, Geographically Explicit Ecological Momentary Assessment (GEMA) studies are gaining momentum. By combining mobile sensors with repeated questionnaires, GEMA allows researchers to link subjective states, behaviours, and physiological indicators to environmental conditions captured in real time – offering new insights into how our surroundings influence our health.
Recognizing the growing importance of this methodology, an international research team led by Yan Kestens, scientific advisor at Polygon, recently published the STROBE-GEMA guidelines in Archives of Public Health1. This extension of the widely used STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement aims to standardize the reporting of GEMA studies to enhance the interpretability, comparability, and reproducibility of both methods and findings. As a company dedicated to providing cutting-edge infrastructure for researchers, at Polygon we’ve ensured that our EMA platform supports the collection of all data necessary to meet these new guidelines.
Why STROBE and reporting guidelines matter
The STROBE statement (STrengthening the Reporting of OBservational Studies in Epidemiology) provides a well-established framework for reporting observational studies, with tailored extensions for cross-sectional, cohort, and case-control studies2,3. Over 20 extensions have been published to better support specific study designs. Presented as checklists and diagrams, these guidelines promote transparency in research practices, enabling critical engagement with the design, methods, and conclusions of a study. Standardized reporting is essential to allow for accurate interpretation and replication of results, valid comparison, and cumulative progress across studies in different contexts.
Gaps identified in GEMA reporting
To develop the STROBE-GEMA guidelines, the research team first conducted a systematic review of GEMA studies linking momentary assessments with geolocated environmental data. The review identified frequent omissions, such as vague descriptions of the technologies used for data collection, insufficient detail on prompting protocols, and a lack of clarity on how location data was obtained – all of which impede replication.
Developing STROBE-GEMA guidelines together: a collaborative process
The research team compared variables extracted from their systematic review with items from the original STROBE and from CREMAS (CRedibility of Evidence from Multiple Analyses of the Same data), which provides specific guidance for reporting EMA studies4. Recognizing that CREMAS, although an important contribution to the field, did not adequately address the spatial aspects inherent to GEMA studies, the team developed a tailored extension applicable to EMA studies that includes location data.
The resulting guidelines include 27 categories and 70 items, integrating the original STROBE and relevant CREMAS items, while introducing 32 new items specific to GEMA studies. One key addition is a new “Consent” category, highlighting ethical considerations related to collecting and reporting location data. To ensure the guideline's validity and comprehensiveness, the team engaged an international panel of experts in a Delphi-like consultation process involving multiple rounds of feedback and refinement. This iterative approach ensured that the final STROBE-GEMA guidelines reflect broad consensus on essential reporting practices in this emerging field.
What sets STROBE-GEMA apart — and how our EMA platform measures up
The STROBE-GEMA article provides guidelines for detailed reporting on:
- data collection technologies (e.g., smartphone, wearable), GPS specifications, and whether devices were provided to participants;
- parameters for location data collection: data sources, recording intervals (momentary vs. continuous), and the proportion of valid geolocated responses ;
- methods for deriving environmental exposures from GPS coordinates, including use of buffer calculations, spatial overlays, or other techniques, and how these are temporally linked to EMA responses;
- procedures for handling missing GPS data and assessing bias from selective mobility or technical limitations;
- ethical protocols, particularly regarding informed consent and location data precision.
At Polygon, we understand the critical importance of thorough and transparent reporting in GEMA research. Our EMA platform is designed to support full compliance with STROBE-GEMA guidelines, allowing researchers to capture:
- detailed information about the devices used and their configurations;
- precise GPS coordinates and metadata (where available);
- accurate timestamps for both prompts and responses;
- comprehensive reports on prompting strategies and compliance rates;
- metadata on potential data collection issues (e.g., missing GPS data).
By using our infrastructure, researchers can be confident that their data collection and reporting meet the STROBE-GEMA standards, fostering greater clarity and credibility in their published work.
Supporting researchers from start to finish
Beyond our tools, Polygon offers in-house expertise in GEMA study design and execution. We’re here to support researchers at every stage – from planning to deployment to analysis and publication – ensuring that their methods are sound and their findings clearly and reliably reported, in line with STROBE-GEMA guidelines.
Working together for greater clarity in GEMA research STROBE-GEMA guidelines represent a significant step forward in establishing best practices for reporting GEMA studies. By embracing these recommendations and leveraging compliant tools like our EMA platform, the research community can collectively build a more robust and reliable body of evidence on the critical links between our environments and health.
Interested in leveraging our platform for your next EMA or GEMA study? Let’s connect! We’d love to hear about your goals and explore how we can support your research.
References:
1. Kingsbury, Célia, Marie Buzzi, Basile Chaix, Martina Kanning, Sadun Khezri, Behzad Kiani, Thomas R. Kirchner, Allison Maurel, Benoît Thierry, and Yan Kestens. 2024. “STROBE-GEMA: A STROBE Extension for Reporting of Geographically Explicit Ecological Momentary Assessment Studies.” Archives of Public Health 82 (1): 84. https://doi.org/10.1186/s13690-024-01310-8.
2. “Equator Reporting Guidelines - STROBE.” Equator network. Accessed April 24, 2025. https://www.equator-network.org/reporting-guidelines/strobe.
3. “STROBE - Strengthening the reporting of observational studies in epidemiology.” STROBE. Accessed April 24, 2025. https://www.strobe-statement.org.
4. Liao, Yue, Kara Skelton, Genevieve Dunton, and Meg Bruening. 2016. “A Systematic Review of Methods and Procedures Used in Ecological Momentary Assessments of Diet and Physical Activity Research in Youth: An Adapted STROBE Checklist for Reporting EMA Studies (CREMAS).” Journal of Medical Internet Research 18 (6): e4954. https://doi.org/10.2196/jmir.4954.
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