Download - Presentation evidence base website
![Page 1: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/1.jpg)
Drug and alcohol prevention
How do we find out what works?
![Page 2: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/2.jpg)
Many people worry about the use of drugs (including alcohol and tobacco) by young people
![Page 3: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/3.jpg)
There are many interventions - in schools, families and the community - which claim to
reduce drug misuse.
![Page 4: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/4.jpg)
?
?
How can we test whether they actually work?
?
?
![Page 5: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/5.jpg)
Higher quality trials give more certainty about results
Best practice
Before and after data
Before and after data with a control group
Randomised controlled trial
Statistically matched control group
![Page 6: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/6.jpg)
Percent drinking alcohol in past week
Measure outcomes before and after intervention
Before After0%
1%
2%
3%
4%
5%
3.5%4.0%
Intervention
What does this tell us?
Very little without a control group.
![Page 7: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/7.jpg)
Before After0%
1%
2%
3%
4%
5%
3.5%4.0%
3.2%
4.7%Percent drinking alcohol in past week
With a control group...
Intervention
Control
Smaller increase in drinking in intervention group
![Page 8: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/8.jpg)
What do we know about the control group?
The following methods give increasing confidence that the comparison is a fair one:
• Common sense – avoiding obvious pitfalls such as those trying out the intervention tending to be in more prosperous areas.
• Statistical ‘matching’ techniques using more information about individuals in the groups.
• Random allocation between the intervention and control groups: this is called a “Randomised controlled trial”
![Page 9: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/9.jpg)
Randomised controlled trials (RCTs) are the ‘gold standard’ for measuring impact
![Page 10: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/10.jpg)
Sample size matters• This is because a behaviour (for example drinking in
the past week) will vary between individuals across the wider population.
• If a sample of 1000 15 year olds in London are randomly selected and 200 (20%) drank in the past week, you can be confident that the true percentage for all 15 year olds in London is fairly close to 20%.
• In contrast, if you select ten young people at random and two of them drank in the past week, that doesn’t tell you much at all.
![Page 11: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/11.jpg)
Statistical analysis• So, as well as looking at the size of the difference
between your intervention and control groups, the size of your sample is also important.
• Larger samples give more confidence that the difference between two groups is genuine and not due to random variation.
• Once it is calculated as being sufficiently unlikely (less than a 5% chance) that the result is due to random variation, the finding is said to be ‘statistically significant’.
![Page 12: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/12.jpg)
Find out more...• The Centre for Analysis of Youth Transitions (CAYT) is
creating a repository of impact studies on young people’s services and programmes - http://www.ifs.org.uk/centres/caytRepository
• European Quality Standards have been developed for drug prevention and contain useful information on evaluating outcomes. http://www.emcdda.europa.eu/publications/manuals/prevention-standards
• ‘Test, Learn, Adapt: Developing Public Policy with Randomised Controlled Trials’ is a more general discussion of RCTs in public policy http://bit.ly/MHJ4aP
![Page 13: Presentation evidence base website](https://reader038.vdocuments.net/reader038/viewer/2022103110/54937295ac79593b2e8b4851/html5/thumbnails/13.jpg)
www.mentoruk.org.uk@mentortweets
1st floor, 67 – 69 Cowcross StreetLondon EC1M 6PU
Registered Charity No: 1112339Registered Company No: 5609241Scottish Charity No: SC041210