In the field of mental health, interventions (e.g., support groups) and products (e.g., digital apps) aim to improve people’s mental health, well-being or quality of life. But, how do you know if they actually have a positive impact?

To investigate whether an intervention or product has led to change, you can conduct a before-and-after study (also called pre-post study). The UK Health Security Agency describes a before-and-after study as measuring an outcome variable in a group of participants before introducing an intervention or product, and then again afterwards. Examples of outcome variables are mental health, well-being or quality of life measurements. If you observe a change in your outcome variable, you may conclude it was due to the product or intervention. However, it cannot be ruled out that something else might have caused the change, such as unexpected life events or improved access to treatment or social support.

Diagram showing One-Group Pretest-Posttest over time: Group A, Pretest, Treatment X, Posttest

To conduct a before-and-after study, you should use the following steps as a guide:

  1. decide on the outcome variable you want to improve through your intervention
  2. recruit your sample
  3. get informed consent
  4. assess your outcome variable before starting the intervention
  5. deliver the intervention
  6. assess your outcome variable when the intervention is complete
  7. run your data analysis and compare your findings from before and after the intervention

For example, McKechnie and colleagues conducted a before-and-after study to investigate the effectiveness of an internet support forum for carers of people with dementia. They expected that using this forum for twelve weeks would decrease anxiety and depression in carers and change the quality of the relationship between the carer and the person with dementia. The researchers recruited a sample of 61 new forum users who gave informed consent to participate in the study. The forum users first completed questionnaires on the outcome variables of anxiety, depression and quality of relationship before starting the intervention. Then, they used the forum for twelve weeks. After using the forum, they completed the same questionnaires on anxiety, depression and quality of relationship again. The researchers ran their analysis and found that using the forum improved the quality of the relationship with the person with dementia. But they did not find change in users’ depression or anxiety over the 12-week study period.

(Author: Leonie Ader)

What is it?

Videos:

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What is a One-group pretest/posttest research design (pre-experimental research)??” by Search Research (2021)

This video briefly describes the pretest/posttest research design (equivalent to before-and-after study) using two specific examples.

(Academic reference: Search Research (2021, May 17). What is a One-group pretest/posttest research design (pre-experimental research)?? [Video]. YouTube. https://www.youtube.com/watch?v=JkOj6hA-Gq8&ab_channel=SearchResearch)

Websites:

Before-and-after study: comparative studies” by UK Health Security Agency (2020)

This article includes a comprehensive definition of the before-and-after-study design, what to use it for, Pros and Cons of the study design, how to carry out a before-and-after study as well as a real-world example.

(Academic reference: UK Health Security Agency (2020, January 30). Before-and-after study: comparative studies. GOV.UK. https://www.gov.uk/guidance/before-and-after-study-comparative-studies#:~:text=A%20before%2Dand%2Dafter%20study%20(also%20called%20pre%2D,to%20the%20product%20or%20intervention)

How is it done?

Presentation:

Pre-post outcome analyses” by Russell Cole (2020)

This high-level presentation describes how results from before-and-after studies can be analysed.

(Academic reference: Cole, R. (2020). Pre-post outcome analyses [PowerPoint slides]. https://opa.hhs.gov/sites/default/files/2020-07/tpp18-pre-post-webinar-slides.pdf)

Method in action

Videos:

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Pre-Post Test Graphs” by Greg Marchant (2013)

This video shows how to calculate graphs for a before-and-after study (pre-post test) using Excel.

(Academic reference: Marchang, G. (2013, March 20). Pre-Post Test Graphs [Video]. YouTube. https://www.youtube.com/watch?v=4yZv6rx-vaw&ab_channel=GregMarchant)

Articles:

The Effectiveness of an Internet Support Forum for Carers of People With Dementia: A Pre-Post Cohort Study” by McKechnie and colleagues (2014)

This academic journal article is the full description of the before-and-after study described in the text.

(Academic reference: McKechnie, V., Barker, C., & Stott, J. (2014). The effectiveness of an Internet support forum for carers of people with dementia: a pre-post cohort study. Journal of Medical Internet Research, 16(2), e3166.)