Content

Interventions

Key Public Health Questions

What works to prevent the issue?

What works to reduce the impact of the issue on the community?

Use this step if you are:

  • Understand which injury issue you will focus on
  • Understand the issue and its extent
  • Understand the causes of the issue
  • But are unsure of the effective solutions.

This section  is divided into two sections:

  1. Describes what an intervention is, details how you can determine the target audience, aim and objectives of your intervention; and helps you determine what type of intervention you want to develop
  2. Describes how you determine what specific intervention you could develop that will best met your needs.

What is an intervention?

In steps one and two of the Public Health Approach to Injury Prevention you would have developed an understanding of what injury area needs attention, learnt about the issue, the magnitude and extent of the problem and its causes and determinants. This third stage of the Public Health Approach to Injury Prevention is about developing an intervention to address the issue.

An intervention is a combination of activities designed to change behavioural, environmental and/or social determinants to improve the health status of individuals or populations by influencing the target audience to lessen the impact of injuries.

Crucial to the development of an intervention is:

  • Defining a target audience – based on the information from the previous sections regarding the extent and magnitude of the problem.
  • Determining a purpose (including aims and objectives)–again based on the information from the previous sections but details what it is you are hoping to achieve, it details what you want to see happen as a result of doing something.
  • Determining intervention types and components that can be developed to influence your target audience for a particular purpose.

The target audience for the intervention

For projects to be successful, it is essential that there is a clearly defined target audience in whom a certain change can be measured. Not all populations are at the same risk of injury; hence it is appropriate to consider which audience your intervention will target:

Universal interventions are accessible by whole population who have not been identified on the basis of individual risk. 1 For example, universal interventions may target workplaces, childcare centres, schools, or whole communities such as anti-bullying policies.
Selective or targeted interventions are aimed at more specific sub-population known to be at greater risk of a particular injury For example, selective interventions may target new immigrant families regarding surf safety.
Indicated interventions refers to interventions aimed at targeting individuals who are identified (or individually screened) as at imminent greater risk of an injury. For example, information and referral service for young people caught drink driving.

It may be worthwhile describing your target in very specific terms; this is often referred to as target audience segmentation.  It is the process of breaking down the broad target audience into smaller subgroups according to relevant variables.  These variables may include:

Variables

Demographic Pyscho social
Age Attitudes
Gender Lifestyle preferences
Aboriginal Status Stages of change (preparedness to change)
Geographical Location Behaviours
Country of Birth/Language spoken at home

Much of this information you will have collated from the previous two planning steps, surveillance and determinants.  Using community consultation as detailed in these steps helps you to gain a thorough understanding of the issue being addressed and the barriers and facilitators of adopting the targeted behaviour through the eyes of the target audience – a process that allows a thorough exploration of knowledge, beliefs, attitudes and behaviours relevant to the issue.  This also helps inform the target segmentation.

This process allows you to identify the most appropriate key target audience segments for your intervention.  It allows you to make decisions about which segments of the target audience should be your primary focus so you can achieve the greatest impact both in terms of health outcomes and return on campaign investment.

You may also like to describe both a primary target audience (with the appropriate levels of segmentation) and a secondary target audience.  To distinguish the difference:

Primary target audience – is the segmented targeted audience who you are trying to have the greatest influence on by developing an intervention for them to use or be influenced by.

Secondary target audience – is the target audience of influencers who can help you reach your target audience or have the ability to influence the determinants of the issue.

Example:

Campaign: National Binge Drinking Campaign

Primary target audience:

Teenagers aged 15 – 17 years; and young adults aged 18-25 years; based on evidence that a high proportion of the alcohol consumed by these age groups is at risky and high levels

Secondary target audience:

Parents of 13 -17 years; based on evidence that suggests parents can influence their teenagers drinking, teenagers look

Purpose of the intervention

Clearly establishing your project or interventions main purpose at the beginning is essential.  This section will outline the definition of the aim of the project and its objectives, and it will also describe how to write specific and measurable aims and objectives to help guide your project.

Aim

An aim is a broad statement on a long-term outcome that relates to the improvement of health or safety status in a population.2 Purpose of goal is another word commonly used. An aim can be a change in mortality or morbidity rates, disability, quality of life or equity. For more details see Learn – Surveillance.

An aim is evaluated in terms of outcome evaluation. For more details see Learn – Evaluation.

Aims are achieved through a range of objectives.

Objectives

Objectives are more operational and are medium-term changes that you would like to see to help achieve your aim. Objectives address determinants; those factors that cause or contribute to the injury area that is addressed in the aim. See Learn – Determinants for more details. Check out this useful document to help you write an objective. Objectives also need to be SMART.

Objectives are evaluated in terms of impact evaluation. For more details see Learn – Evaluation.

Writing objectives follows a formula, which is: “To do what, for whom, by when”

The language used should be selected carefully to provide a clear understanding of what the objective will achieve. Example of words that could be used includes the following:

Introduce  Create Establish Advocate Develop
Increase  Improve Decrease Eliminate Facilitate
Support  Initiate Participate Reduce

A good way to test how effective your objectives are is to make sure they follow the SMART formula. The SMART formula contains the following characteristics.

Are your objectives:

S – Specific: Does it state clearly what you are doing, for whom, by when?

M – Measurable: Does it include a feature that will let you know whether or not it has been successful?

A – Attainable: Can it be realistically achieved with your current resources?

R – Relevant: Does it logically relate to your overarching goal?

T – Time-specific: Does it have a timeframe in which the change will occur?

The following is an example of an injury-specific objective which satisfies all of the SMART formula.

To increase knowledge of water safety in culturally and linguistically diverse children aged 8 to 12 in Western Australia by February, 2018.

S – Specific: This objective states clearly what will be increased, in whom and by when.

M – Measurable: Assuming there is a baseline measure, then an increase in knowledge is relatively easy to evaluate.

A – Attainable: Assuming the organisation who wrote the objective is resourced appropriately.

R – Relevant: The objective logically relates to an overarching goal to reduce drownings.

T – Time-specific: The date that the change is hoped to be achieved by is clearly stated.

Activities and strategies undertaken to achieve these objectives are collectively called the intervention.

Intervention components and types

Interventions or strategies are short-term activities aimed at achieving an objective.

Intervention is evaluated in terms of process evaluation. For more details see Learn – Evaluation.

Interventions Aims

Effective approaches often involve a mix of interventions at multiple levels (from the individual through to populations).1 There are numerous frameworks that can help you develop and structure appropriate intervention(s). Below is a selection:

  • Levels of prevention (primary, secondary and tertiary)
  • Upstream, midstream and downstream action
  • Passive versus active measures
  • Ottawa Charter
  • Three E’s of Safety.

Levels of intervention: Primary, Secondary and Tertiary Prevention

Prevention can be defined as action to reduce or eliminate the onset, causes, complications or recurrence of disease.4 Prevention interventions are generally designed to reduce the likelihood that something harmful will occur, or to minimize that harm if it does occur. These interventions are often categories along the injury continuum, as shown in Figure 1.

Figure 1: Injury continuum

Stage of Injury

Pre-injurious event

Injurious event

Post-injurious event

Target audience Populations which are safe or not injured Populations at-risk or vulnerable or recently injured Population who have been injured and are recovering
Level of prevention Primary Prevention Secondary prevention Tertiary prevention
Other terminology Safety promotionInjury prevention Injury preventionFirst response and initial treatment Injury managementRehabilitationPost-injury support

There are three different stages of along this continuum in which interventions can take place. These are primary, secondary and tertiary.

Primary prevention aims to prevent an injury from occurring in the first place, by altering exposure to the risk and protective factors. This may involve limiting the incidence in the population, eliminating or reducing the causes or determinants, controlling exposure to risk or promoting factors that create safe environments. 5,6

Secondary prevention interventions involve early detection and prompt intervention to correct departures from being safe or the treatment of initial injuries. It may also involve first response from those involved or the initial treatment of an injury. Secondary prevention may also involve ensuring those who have already been injured from being injured again.

Tertiary prevention interventions involve lessening the impact of an injury, which has occurred, and preventing a reoccurrence. It may also involve supporting survivors cope with an injury-related loss, rehabilitation or post-injury support to prevent relapse or depression.6

Upstream, midstream and downstream action

Safety promotion, injury prevention and injury management are terms also used along with upstream, midstream and downstream. These align with primary, secondary and tertiary prevention. 7

As discussed in the Learn – Determinants Section the simple river analogy can be applied to understanding potential interventions. Watch this short video on upstream, midstream and downstream determinants of health.

For example, upstream determinants are those that occur at the macro level and include global forces and government policies. When we look upstream it can reveal why people are falling into the water – the root cause of the injury. Upstream interventions therefore aim to eliminate the harmful event from ever occurring. It aims to remove the circumstances causing an injury. This type of action usually targets (though not always) populations who are generally safe and healthy or who are at a lesser risk of being exposed to a harmful event. This is primary prevention.

Midstream determinants are intermediate factors such as health behaviours while downstream determinants occur at the micro level and include one’s genetics. When we look midstream we notice that people are either about to or are already struggling in the water. Midstream interventions aim to reduce the severity of an injury should one occur. This type of action usually targets populations who are more vulnerable or at risk of being injured. This is secondary prevention.

Downstream determinants are characterized as short-term, problem-specific, individual-based interventions, and challenged health professionals to refocus and look upstream, where the real problems lie.8

An example of upstream, midstream and downstream actions is provided in Figure 1.8

Click here to download the Know Injury – downstream, midstream, upstream actions template

Passive versus Active Measures

When designing interventions, both active and passive measures can be used.

Active measures are those that require people to be compliant on a continuing basis to be effective.

Passive measures conversely, are only applied once and in general, are more effective as people do not need to remember to continue to use of abide by them.

Below are some examples of passive and active measures:

Self-closing gates within pool fences are passive measures for preventing drowning as they do not require continuous implementation of the measure. Contrasting this, supervising children while in the water is an active measure as it requires people to continuously implement the measure.

When building a property the installation of fire walls and doors are passive measures for fire protection as they make it difficult for a fire to spread throughout the building. Centering on alerting occupants about a fire and attempting to put out a fire, active measures for fire protection include fire alarms, sprinkler systems and fire extinguisher systems.

Seat belts are an active measure for preventing road trauma injuries as they require active use, while a cars airbags are a passive measure as once installed if no damage occurs to the airbags they do not require active use.

Ottawa Charter

The Ottawa Charter offers a useful model for framing interventions. The charter is a framework with five action areas for health promotion, which can be applied to injury prevention interventions. These areas are:

  • Building healthy public policy: Ensuring policy is conducive to health and safety.
  • Creating supportive environments: Ensuring environments in which people live and work are structured in ways that support health and safety.
  • Strengthening community action: Encouraging community members to take control of their health and safety.
  • Reorienting health services: Including preventive measures in existing health services, such as general practitioner clinics.
  • Building personal skills: Educating people on prevention practices.9

For more information read WHO Ottawa Charter.

Intervention Ottawa Charter

These five action areas have been adapted below with specific Western Australian examples provided.

Healthy and Safe Public Policy

Legislation and policies: reinforce and encourage safe and healthy choices. They are government set laws that must be followed which will incur a criminal penalty if broken. It is important that legislation is conducive to healthy choices and safeguards people from harm as much as possible.

The Department of the Premier and Cabinet has a database where all relevant legislation can be searched.

For example, speed limits on roads are an effective legislative measure that reduces crashes on our roads. The Road Traffic Act can be found here.

Standards and Codes of Practice: Governing or peak bodies usually set standards. Standards are a criterion of quality that an organisation or practitioner must meet, to ensure best practice and adherence to safety procedures. While a criminal penalty may not necessarily occur, quality of work and safety may be compromised in the event that these codes of practice are not followed.

For example, Safework Australia is a government body that outlines safe practices to minimise workplace injuries. Their Model Code of Practice: How to manage work health and safety risks can be found here
Safe supportive environments, communities and organisations

Environmental design: Healthy and safe options need to be the easier choices in environments where people live, work and play. It is also important that our environments are designed with safety as a key priority.

For example, CPTED guidelines, which stands for Crime Prevention Through Environmental Design provide guidance on creating safe supportive environments including interventions such as effective lighting in public areas. For more information about see the guidelines.10

Campaigns and community initiatives: are used by practitioners to educate communities about safe choices and empower people to develop the skills necessary to live safe and healthy lives. Social marketing uses traditional marketing techniques to promote a health message and encourage people to adopt a new safe behaviour or change an old unsafe one.11

 An effective social marketing campaign in health education would be the WA-based preventative mental health campaign, Act Belong Commit, which encourages people to take better care of their own mental well-being through community involvement.12  You can find out more about this campaign here.

Advocacy and lobbying: has no one strict method however is rather a combination of strategies aimed at promoting a cause. Advocacy and lobbying can be an effective tool in instigating legislative change and sparking public debate with the community and decision makers in charge of policy.13 This can take the form of physical campaigning or online advocacy.

 For example, the McCusker Centre for Action on Alcohol and Youth, in partnership with community members is currently lobbying the Western Australian government to introduce secondary supply laws of alcohol to minors, through social and visual media strategies. For more information about effective advocacy strategies, contact the Public Health Advocacy Institute of Western Australia.12

Community development is the process working with groups and community members to build skills that drive positive change on a local level and empowering communities to meet their own needs.

 An example of a community development project aimed at promoting safety for young people to help build life skills, such as those run by the City of Gosnells, more information about which can be found here.

Organisational and health service initiatives: promote safe behaviours within an organisation and reorienting health services to include prevention programs.

 An example is the Stay on Your Feet®’s sector development program which trains physiotherapists and health professionals who work with older adults in health settings about how to prevent falls in the home, and provides resources about effective falls prevention strategies to health services. More information about this program’s services for other health organisations can be found here. 
Group and Individual Initiatives

Group and individual initiatives are aimed at directly educating and promoting safe lifestyle choices in groups and individuals.

Health education and skills development: is about educating the community about what safe behaviours they can do in their day to day activities and how to develop these skills to encourage individual action.

 An example of a skills development initiative is First Aid training provided to the general public for a range of purposes, including caring for injured people at a road crash.Another example is training people in fitting child car restraints provided by Kidsafe WA. More information about this can be found here.15

Screening and individual risk assessment: this is about equipping practitioners and/or people with the knowledge and skills to assess their own level of injury risk.

 A good resource for assessing risk of falls in hospitals is the Falls Risk and Management Plan which can be located on the Stay On Your Feet® website.

Support for people post-injury: Some injuries such as road trauma can be quite traumatic for those involved, therefore post-injury support is required. This can be in the form of medical treatments or grief and trauma counselling.

Example, Road Trauma Support WA provides support workshops and grief counselling to people affected by road trauma. This includes people who are directly involved in and also bereaved by road crashes.  Road Trauma Support WA website can be accessed here. 16

The Three E’s of Safety

The Three E’s provides another useful way of classifying interventions. The Three E’s stand for:

Environment: Modifying the design of environments to make sure they are safe for people to use on a daily basis.

For example: modifying backyard environments so that all pools are adequately enclosed.

Enforcement: Enforcing legislation to influence individuals and organisations to reduce the risk of injury.

For example: it is Western Australian law that all backyard pools be closed off by adequate fences which are self-closing. Similarly, doors and windows leading to the backyard must also be self-closing.

Education: The aim of education is to increase knowledge and change attitudes to ultimately encourage behaviour change.

For example: educating parents about supervision around pools, as well as children in water safety behaviours.

A note about “selecting an intervention”It is likely that you have come to this point of the planning process and you have a very clear idea about where you want your intervention to “influence” and what type of intervention you want to develop.BUT just in case you need some help – here are some resources to guide you:Portfolio Planning Approach: The portfolio planning approach is used in public health and operates on the premise that it follows that resources should be allocated to where they will have the greatest impact – that is where the cost per unit of outcome (however that is defined) is lowest. There publication contains a decision process to help you determine what this might be for your possible interventions. Click here for more information.Decision Tree Analysis Decision trees are structures that allow options and potential outcomes associated with these options to be visually represented. 17  All decision trees start with the decision that needs to be made and then the possible solutions branch off this decision. At the end of the branch potential results are considered. When developing the tree a square is placed around decisions and a circle around all uncertain outcomes. 18 As the tree grows more decisions may appear resulting in more possible solutions and potential results.Analysing the decision tree allows the option with the greatest worth to be identified. 7

How to develop your specific intervention?

Once your aim and objectives are clear, and you have worked out what type of intervention or which activities you want to develop the next step is to determine exactly what you want to develop. This can be informed by:

  • Learn from the research and experiences of others
  • Use theories and models to design your intervention

Research and evidence

Perhaps the easiest way to do this is to learn from what others have done before you – don’t reinvent the wheel if you don’t have to.  There are a number of ways you could do this, depending on how much time for planning you have, what resources you have available to you and what you think is likely to gain support from your internal stakeholders (something you may have likely explored when you looked at the environmental context in Learn – surveillance)

What is listed below provides the most inclusive way of learning from others19, but obviously you can adapt it to your own circumstances:

1 Literature, evidence, meta reviews These reviews provide you with a evidence synthesis of what has worked or not worked in the area in which you are interested.  Naturally not all injury related topics have had reviews of the evidence published; but this should not prevent you from having a look in the literature to determine what is known about your topic of interest in the form of peer reviewed papers and collating the findings yourself to assist you in thinking about what interventions have been shown to be effective
2 Grey literature reports and compilations Grey literature refers to reports, websites and information that is available but not published in the peer reviewed literature.  It often contains a wealth of information from like minded organisations who have undertaken an evaluation of an intervention they have undertaken but have not had any reason to publish it in journal form.  Often you can find out about these kinds of reports through doing a google search or searching particular websites or contacting people in the same field as you.  Again there is value in collating the findings of such reports to assist you in thinking about what interventions have been shown to be effective
3 Expert opinion There is a lot research that goes unpublished and lots of information that may best be accessed by talking to key experts or opinion leaders in your field; they may be able to offer a good synthesis of what they know to be effective in the area in which you are interested.
4 Stakeholder consultation As has already been mentioned in previous sections, stakeholder consultation is a valuable for a number of parts of the planning process this section included.  Key stakeholders are often able to offer their informed opinion about what has worked previously, what have been the barriers and facilitators of previous interventions.  This particularly valuable if you can discuss with them a design of an intervention that you have developed based on the evidence, and then you can seek advice specifically on how such an intervention could be implemented within your local context.
5 Consumer engagement and formative research There is considerable merit in not only have an in-depth understanding the target audience and the issue; but also understanding from the target audience what they think could be done about it.  In a similar way to that of the stakeholder consultation process; if you are able to seek their feedback on an intervention that you have developed based on the evidence, then their engagement will provide more specific information about what you are able to do with a greater guarantee of success within your local context.

See Learn – Surveillance for details on these approaches.

Things to consider when reviewing other interventions 20:

  • Appropriateness
    • Does the intervention align with your aim and objectives?
    • Does the intervention align with your target audience?
  • Effectiveness
    • Did they evaluate the intervention and did it make a difference?
  • Efficiency
    • What type and quantity of resources did they have to implement the intervention?
  • Barriers and enablers
    • What barriers, resistance, challenges did the implementers face?
    • What enablers helped the implementation of the intervention?
    • What help or hindered their intervention?

Models and theories

As has been previous described in the Learn – Determinants section, models and theories can be used as a tool to help explain or predict a determinant, an event or situation. Theories and models are also useful for design, planning, implementing and evaluating interventions. Below is a selection of common models or theories of change which you may be able to use to inform your initiative.

Stages of Change Theory

The Stages of Change theory, also known as the Trans-theoretical Model, explains the behaviour change process by exploring five stages of change.21 These are;

  • Pre-contemplation (not ready for change)
  • Contemplation (getting ready for change)
  • Preparation (ready for change)
  • Action
  • Maintenance

More information about the Stages of Change theory can be found here.

Health Belief Model

The Health Belief Model is one of the most widely used health promotion theories. The theory is based around an individual’s perceptions and attitudes towards a health issue or a negative consequence of a certain behaviour.22

The theory states that behaviour change will occur with three simultaneously existing ideas, which are:

  1. Perceived severity, i.e. a person recognises there is a cause for concern.
  2. Perceived threat, i.e. a person understands that they are at risk.
  3. Perceived benefits, i.e. a person realises that a change in behaviour can be beneficial for them.

More information about the Health Belief Model can be found here.

Resources and Tools

Public Health Advocacy Institute of Western Australia: Advocacy Toolkit

Public Health Bill 2014: Professor Tarun Weeramanthri, Chief Health Officer, Department of Health WA provides a summary of what the bill will achieve.

How to develop networks and partnerships by Mog Piasecka, Stakeholder Engagement Coordinator, City of Melville

How to influence behaviour by Dr Linda Portsmouth, Lecturer and Researcher, Curtin University

References

O’Connell ME, Boat T, Warner KE (2009) Preventing Mental, Emotional, and Behavioral Disorders Among Young People: Progress and Possibilities. Retrieved from http://www.ncbi.nlm.nih.gov/books/NBK32789/

2 Integrated Health Promotion Resource Kit (2008) Department of Human Services, Victoria. Retrieved from http://docs2.health.vic.gov.au/docs/doc/8196B97B654C907BCA257A7F001DF6E4/$FILE/integrated_health_promo.pdf

3 Writing Measurable Objectives (2010) Department of Health, Victoria. Retrieved from http://www.health.vic.gov.au/regions/southern/downloads/Tip-sheet-writing-measurable-objectives.pdf

4  Australian Institute of Health and Welfare (2004). Australia’s Health 2004, Australian Institute of Health and Welfare. Cat. NO. AUS 44, p496

5 Standard 7: Health Promotion and Illness Prevention (2013) Medicare Locals. Retrieved from http://www.medicarelocals.gov.au/internet/medicarelocals/publishing.nsf/Content/ML-accreditation-standards~standard7#.VXjeH_mqpBd

6 Strategic Plan 2013 (2013) Parachute Canada. Retrieved from http://www.parachutecanada.org/downloads/corporate/Strategic_Plan_-_Website.pdf

7 Svanstrom, L.O and Haglund, B.J.A, (2000) Evidence-based safety promotion and injury

prevention – an introduction. Retrieved from http://www.ki.se/csp/pdf/Books/EvidenceBasedSkadeprevEngvers.pdf

8 Addressing the Social Determinants: Victorian Healthcare Association Population Health Planning Framework (n.d.) Victorian Healthcare Association. Retrieved from http://www.populationhealth.org.au/index.php/component/docman/doc_download/5-social-determinants?Itemid=

9 Ottawa Charter for Health Promotion (2015) Better Health Channel; Department of Health, Victoria. Retrieved from http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Ottawa_Charter_for_Health_Promotion?open

10 Designing Out Crime Planning Guidelines (2006) Western Australian Planning Commission. Retrieved from http://www.planning.wa.gov.au/dop_pub_pdf/docguidelines.pdf

11 What is Social Marketing? (2010) NSMC. Retrieved from http://www.thensmc.com/content/what-social-marketing-1

12 What is Act Belong Commit? (2011) Act Belong Commit. Retrieved from http://www.actbelongcommit.org.au

13 What we do (2015) Public Health Advocacy Institute of Western Australia. Retrieved from http://www.phaiwa.org.au/about-us-2/2012-06-07-12-03-23/what-we-do

14 Holiday programs (2014) City of Gosnells. Retrieved from http://www.gosnells.wa.gov.au/Lifestyle/Get_involved/Children/Holiday_Programs

15 Child car restraints (2008) Kidsafe WA. Retrieved from http://www.kidsafewa.com.au/childcarrestraints.html

16 Road Trauma Awareness and Support (2013) Road Trauma Support Western Australia. Retrieved from http://www.rtswa.org.au/

17 Timmreck, T. (2003). Planning, Program Development, and Evaluation: A Handbook for Health Promotion, Aging, and Health Services. Jones & Bartlett Learning.

18 Miller, R. (2012). Epidemiology for Health Promotion and Disease Prevention Professionals. Routledge Publishing.

19 Adapted from O’Hara, B. J., Phongsavan, P., King, L., Develin, E., Milat, A. J., Eggins, D., … & Bauman, A. E. (2014). ‘Translational formative evaluation’: critical in up-scaling public health programmes. Health promotion international, 29(1), 38-46.

20 Section 1: Designing Community Interventions (2014 Community Tool Box. Retrieved from http://ctb.ku.edu/en/table-of-contents/analyze/where-to-start/design-community-interventions/main

21 Health Promotion Unit. (2007). Stages of behaviour change: Queensland Stay On Your Feet®

Community Good Practice Toolkit. Division of Chief Health Officer, Queensland Health. Retrieved from http://www.health.qld.gov.au/stayonyourfeet/documents/33331.pdf

22 Glanz, K. et al. (2002). Health Behavior and Health Education. Theory, Research and Practice.

San Fransisco: Wiley & Sons.

23 Ajzen, I., Albarracin, D., Hornik, R. (2012). Prediction and Change of Health Behaviour: Applying the Reasoned Action Approach. Psychology Press.

24 Brannon, L. and Feist, J. (2009). Health Psychology: An Introduction to Behavior and Health. 7th Edition. Cengage Learning.