Report
Phase 4: Illegal Gambling Index – Technical Report
The Gambling Commission’s technical report detailing the development of the Illegal Gambling Index.
Strengths and limitations
Strengths
We have used a multi-phase process, with methodologies spanning qualitative depth, quantitative rigour, and data science, to develop this index, using findings from earlier phases to validate and refine the indicators to be taken forward into the the Gambling Survey for Great Britain (GSGB).
Qualitative research: This ensures that all findings are contextualised with a richer, more nuanced understanding. Conducting focus groups with members of the Lived Experience Advisory Panel (LEAP) ensures that those with true lived experience of gambling are represented in the development of the research.
Quantitative research and data science: This ensures that findings have a strong analytical grounding and have enabled the Gambling Commission to develop measurement techniques to understand the illegal gambling market over time.
The development process has consistency engaged with key stakeholders to ensure the index is reflective of the gambling space, through workshops with the Commission’s Lived Experience Advisory Panel (LEAP), their Industry Forum, academic specialists, and researchers within the Commission.
The indicators that form the basis of the index are grounded in real-life behaviours that are associated with illegal gambling websites, rather than solely being based on respondents’ own understanding of the legality of the websites they use.
The index is flexible and can be adjusted to respond to emerging indicators of illegal gambling websites as the industry adapts. It also accounts for varying level of confidence that researchers can have in each indicator, building in context around recall issues through survey design experience and qualitative insights.
Limitations
The index is not intended to be a definitive measure of the size and scope of the illegal gambling market. The aim instead is to identify degrees of confidence in consumer engagement, with the indicators acting as proxies for engagement, rather than explicit evidence.
Consumer understanding and recall of engagement with the illegal market is limited. Qualitative research has previously found that respondents do not always know if, and when, they have used an illegal gambling website, often due to tactics deployed by the company to disguise their legality. Generally speaking, survey recall of beyond 4 weeks is limited; we know that this holds true when respondents are considering their previous gambling behaviour, too.
Qualitative research: Qualitative sample sizes are by their nature small, so conclusions can only be directional, unless contextualised by quantitative data. Qualitative research heavily relies on the skills and experience of researchers, introducing potential researcher bias although this is mitigated by employing a grounded theory approach, where thematic grid analysis is used to capture qualitative data and notes, and where narratives are developed through rigorous analysis of this data. All insights gathered from this study are based on self-reported behaviour rather than observed behaviour, meaning insight is limited to what participants felt comfortable revealing to Yonder in the research setting. While interviews mentioned in this report took place with a range of participants, the focus groups mentioned above took place with either members of LEAP or via their facilitation, meaning the full scope of gambling engagement could not be fully represented.
Quantitative research: Quantitative research provides a valuable snapshot of attitudes and opinions, offering a broad view of trends and patterns across a specific sample. However, one key limitation is that quantitative results often lack the depth to explain why respondents hold certain views or what specific factors drive their responses. The sample selections for the quantitative research also provides limitations in the interpretation of results. The development survey samples selected from Yonder’s research panel were those who had gambled in the past 4 weeks, excluding National Lottery only players. As such, findings from these surveys should not be treated as representative of all those who gamble, and caution should be taken in assessing the significance of sub-group differences such as gambling frequency and Problem Gambling Severity Index (PGSI) score, as these groups may also not be representative, and may represent a higher than natural proportion within the sample than they would in a survey of the general population. This is mitigated against by the inclusion of the GSGB in the development of these statements.
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Last updated: 5 November 2026
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