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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.

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Published
19 April 2023

Last updated
18 April 2023 - Changes

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Contents

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

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• Executive summary
• - Experimentation work
• - Response
• - Assessment of experiment results
• - Recommendations
• Introduction
• - Background
• - Aims and overview
• Methodology and response
• - Survey design
• - Questionnaire content and design
• - Response to the survey
• Testing an alternative approach to the selection of participants within households
• - Introduction
• - Completion rates in responding households
• - Adherence to participant-selection instructions
• - Duplicate cases
• - Household clustering
• - Prevalence of gambling behaviours
• - Conclusion
• Measuring gambling-related harms
• - Introduction
• - Testing different ways of asking about gambling harms
• - Results
• - Conclusion
• Testing different approaches to asking questions about gambling participation
• - Introduction
• - Comparison of gambling participation across the three approaches
• - Potential primacy effect with the long-list approach
• - Additional considerations for the postal questionnaire
• - Other considerations
• - Conclusion

Household clustering

You can view tables referenced in this section by downloading the file Tables A1 to A48 - Gambling Survey - Experimental statistics stage (XLSX)

Measures of household clustering are sensitive to differences in the numbers of completions per household. If more adults take part in multi-adult households, the degree of clustering will increase because some of the additional participants will have similar behaviours to their fellow participating householders. This is important to bear in mind when interpreting these results. As shown previously, C1 (up to two adults) households had an average of 1.47 completions whilst C2 (up to four adults) had an average of 1.51.

The Design Effect (DEFF) is a measure that summarises the degree of clustering that has occurred. In technical terms it is the ratio of the variance between individuals in the (clustered) sample, compared with the variance that would be expected from a simple random sample. A higher DEFF shows a greater degree of clustering of gambling behaviour within households that is more similarity between participants in multi-response households (other things remaining equal).

For each of the activities there was a greater degree of clustering for C2 (up to four adults) households compared with C1 (up to two adults) households. This would be expected given that C2 (up to four adults) households had a larger mean of responses per household (1.51 completions compared with 1.47 for C1 (up to two adults) households). This increased clustering is most notable for those who took part in online gambling (Table A.17 (Design Effect (DEFF) for gambling activities in the last 12 months, by experimental condition) shows the DEFF for gambling activities by the two experimental conditions).

One aim of the experiment was to investigate whether allowing more than two participants per household would attract more of those who did not gamble to complete the survey, particularly in households with at least one person who gambled.

Clustering was much higher in these larger households than it was in the sample as whole. This suggests that when more completions were allowed, there was a tendency for more people with similar gambling behaviours to take part. Notably, the largest difference in the degree of clustering compared with the sample as a whole is for 'any online gambling other than National Lottery within the last 12 months', demonstrating that those who took part in this activity had a higher propensity to respond to the survey (Table A.18 (Design Effect (DEFF) for gambling activities in the last 12 months) shows the DEFF for households with three or four participants (these are only from experimental condition C2).

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Duplicate cases Next section
Prevalence of gambling behaviours

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Last updated: 18 April 2023

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