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Gambling participation and the prevalence of problem gambling survey: Experimental statistics stage

Gambling Commission report produced by NatCen on the experimental statistics stage of the gambling participation and the prevalence of problem gambling survey.

Duplicate cases

On occasion, a household member completed the survey more than once, either by the same or a different mode. These cases are called duplicates. Potential duplicates were manually reviewed to determine whether responses to multiple questionnaires were very likely to be from the same individual in a household (based on exact matches for the age, sex and name provided).

Each responding adult, up to the maximum number permitted for the experimental condition, was given a £10 pounds incentive. Arguably this incentivises participants to make up household members and/or questionnaires to gain an additional incentive.

In total 78 duplications (1.5 percent of total completions) were identified. Duplications accounted for 1.4 percent of C1 (up to two adults) completions and 1.7 per cent of C2 (up to four adults) completions but the difference was not statistically significant. Even with the increased opportunity for C2 households to complete more interviews and claim an additional incentive, this did not seem to be the case (Table not shown).

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Adherence to participant-selection instructions
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Household clustering
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