Report
Phase 4: Illegal Gambling Index – Technical Report
The Gambling Commission’s technical report detailing the development of the Illegal Gambling Index.
Commission modification of the index
Yonder delivered a technical report to the Gambling Commission, outlining the question development process and index calculation instructions. This report was reviewed and scheduled to be published alongside the first illegal gambling Gambling Survey for Great Britain (GSGB) data release of 4 waves of data. This section of the report details the refinements the Commission made either after delivery of the technical report and/or analyses of the first waves of piloted GSGB data using Yonder’s original Illegal Gambling Index.
Upgrading the ‘Not on Gamstop’ indicator
The ‘Not on Gamstop’ indicator was originally coded as ‘Strong’ for the Phase 2 quantitative survey, but Yonder and the Commission agreed that it should be upgraded to ‘Near Certain’ for the Illegal Gambling Index. Individuals using a gambling website they knew was not on Gamstop is considered a valuable indicator of consumer engagement with illegal gambling websites, given that all licensed gambling websites are required to participate in Gamstop.
Removing the questions relating to intentionality from the index
One of the questions piloted in the GSGB asked respondents directly whether they had intentionally used illegal gambling websites. Respondents who reported intentionally gambling on illegal websites in the past 4 weeks were also asked to name the websites they believed to be illegal. The rationale was that this would help to validate whether they had, in fact, used an illegal gambling website. Both questions were tested with key stakeholders during the Phase 2 research and were considered suitable for inclusion in the GSGB.
However, following initial analysis of the first two waves of the piloted GSGB questions, only a small number of respondents reported intentionally gambling on illegal websites. When those who reported doing so in the past 4 weeks were asked to name the illegal gambling website they had used, an even smaller number provided the names of websites they believed to be illegal, with the vast majority selecting ‘prefer not to say’.
For the handful who did provide a website name, analysis showed that many of the websites named were, in fact, licensed gambling operators. This finding is consistent with previous phases of this research, which shows that consumers often lack clarity about what constitutes a licensed versus an illegal gambling website. Furthermore, respondents who selected ‘prefer not to say’ were still able to be identified as potential users of illegal gambling websites through the remaining 7 indicators, meaning the 7 indicators alone provided a sufficiently robust basis for constructing the index, and the intentionality questions were not incorporated into the final index scoring methodology.
Furthermore, the follow-up question (Question A2) asking respondents to name a website was also removed from the question listed due to its limited additional value and redundancy, as all of the individuals identified as having used illegal gambling websites using this question were also captured through the index approach using the remaining 7 indicators.
The removal of the main intentionality question (Question A1) from the index (meaning that the index is now calculated using 7 statements rather than 8) resulted in the threshold for a respondent to be considered as having engaged with illegal gambling websites in the past 4 weeks from 16.7 to 18.75, as is demonstrated in the earlier section Flexing the index for the GSGB.
It should be noted that although Question A1 was removed from the index calculation, the question itself was retained in the GSGB.
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Last updated: 5 November 2026
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