Evidence-based practice

Building our evidence base of 'what works' in prevention is vital to ensuring our work is effective, and underpins all that we do.

What is evidence?

Many people talk about evidence – but what exactly does this term mean? Generally, evidence is intended as any argument or “proof” in support of a conclusion or assertion. It can be seen as information that helps us prove or demonstrate truth – or disprove something that is false.

Evidence is information in support of an assertion. That information can be strong or weak. We want that information to be as strong as possible.

Centre for Youth Impact

Evidence can come in many different forms, linked to different disciplines. There are many different types of evidence, from stories and testimony, to data from surveys or scientific trials. For public health interventions, including prevention science and practice, evidence refers to the effectiveness of an intervention in achieving certain outcomes that contribute to long lasting changes in the population health and behaviours.

Evidence can be “weak” or “strong”. There are different levels of value attached to different forms of evidence, different grades that identify good quality of evidence and that establish what counts as good evidence. That means drafting well-defined standards in order to classify the levels of evidence-based research.

Whatever form or level of evidence we need to describe, it is important to consider the audience for your evidence, and the use you want to make of it.

Why is evidence important?

Evidence is about accountability. Evidence is part of our everyday life and it helps us assess the impact and effectiveness of our work. When it comes to interventions for young people and children, evidence helps us to establish what types of programmes are more effective and can make a positive impact on the lives of our beneficiaries. Through evidence we can learn and improve our practice, increasing the value of our work for funders, commissioners, researchers and, most importantly, for the young people and the families we support.

When selecting prevention programmes for their communities, policy makers, practitioners and health and education professionals need easy access to reliable and independently validated information.

How should evidence be used?

Using solid evidence can help us measure impact, better inform policy guidance and improve professional service delivery. Evidence should be used in the design, delivery and evaluation of programmes targeting young people.

Here are some important principles about using evidence:

  • Evidence is support, not proof or truth, of an assertion
  • Evidence provides a deeper understanding and insight into the impact of our work
  • Evidence gives us opportunities for reflection and improvement
  • Evidence is for anyone, adding value to all those involved in the delivery of, or benefitting from, services

Evidence-based practice in prevention

Evidence-based prevention is one component of an ethical approach to supporting young people. Prevention is, by definition, designed to change behaviour, cognitions and opportunities. Prevention that is not based on evidence of effectiveness, or an approach that has a high probability of being effective, is unethical as it does not provide young people with the support they need and may lead to increased involvement in activities that have negative consequences on health, relationships and life opportunities.

A well-supported evidence-based intervention programme is usually comprised of two components: a strong magnitude of impact, along with a fair and rigorous methodological approach (Nation et al., 2003). In other words, there has to be causal relationship between implementation of the programme and outcomes of the intervention.

“Evidence-based practice” – meaning “best practice” or “with well-supported evidence” – is a crucial element in policy development and the implementation of programmes in the prevention field. When selecting prevention programmes for young people, policy makers, practitioners and health and education professionals need easy access to reliable and independently validated information.

Mentor is working for an effective, comprehensive and national prevention strategy, through families, schools and communities. No magic bullet can prevent a young person experimenting with alcohol or drugs but we want to create an ecosystem of prevention in the UK which increases protective factors and reduces risks.

Mentor advocates for programmes that have been proven by hard evidence to change young people’s attitudes and behaviour to alcohol and drugs and to (re)engage them in education, training volunteering and work.

Types of evidence-based prevention

We want a mix of evidence-based prevention which can have a real impact on young people’s lives.

  • Universal – Aimed at all children and young people, delivered through schools, youth clubs and/or families. See The Good Behaviour Game.
  • Targeted – For higher risk groups. See Families Together.
  • Indicated – For young people showing early signs of substance abuse and other related problem behaviors associated with substance abuse. See Breaking Out.

International evidence on prevention

The following briefing paper provides a summary of the UNODC prevention standards and gives corresponding examples of relevant UK guidelines, programmes and interventions currently available in England. It aims to help those in the prevention field to translate the standards into the English operating landscape. It also aims to support local authority commissioners to develop their prevention strategies and implement them in line with evidence.

Download ‘The international evidence on the prevention of drug and alcohol use – Summary and examples of implementation in England’


 The Alcohol and Drug Education and Prevention Information Service (ADEPIS) is a platform for sharing information and resources aimed at schools and practitioners working in drug and alcohol prevention.

ADEPIS is publicly acknowledged as the leading source of evidence-based information and tools for alcohol and drug education and prevention for schools. The resources we have already produced draw on eight years of work with the Drug Education Forum, which supported local authorities and schools to implement best practice in drug education.

The Centre for Analysis of Youth Transitions (CAYT) has created a repository of quality assured studies that assess the impact of programmes and services supporting the development of young people; these may be delivered in a range of settings, including education settings. ADEPIS took over the management of the repository in April 2015, and will be responsible for its development.

CAYT’s primary aim is to provide education and prevention practitioners with evidence of what has proved – or is promising – to be of good practice; to highlight those programmes showing high effectiveness and rigorous evidence.

To this end, we have revised the original CAYT scoring system. Read more about these guidelines here.

Quality standards for drug and alcohol education

In 2014 Mentor developed the Quality Standards for Effective Drug and Alcohol Education, published through ADEPIS.

These standards have drawn on existing national and international guidance as well as examples of good practice in alcohol and drug education and prevention. In addition, we consulted widely with teachers, practitioners and those that support school alcohol and drug education in order to ensure that they reflect the best current evidence and practice.

What we know

Research has identified some of the things that make young people vulnerable to using alcohol and drugs. These include: being in trouble at school, having friends who take drugs and drink, starting to smoke early, and/or staying out late without parents’ knowledge. Conversely, there are also factors that can protect young people, including good family relationships, clear rules and boundaries and positive school environments.

One powerful protective factor is a strong attachment to school. Mentor believes all children and young people have the right to good alcohol and drug education, which is why we are campaigning for statutory PSHE. We know what works when it comes to delivering good alcohol and drug prevention in schools.

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