Intervention Studies: Epidemiologic investigations designed to test a hypothesized cause-effect relation by modifying the supposed causal factor(s) in the study population. A distinguishing characteristic of an intervention study is that the intervention (the preventative or therapeutic measure) being tested is allocated by the investigator to a group of two or more study subjects (individuals, households, communities). Subjects are followed prospectively to compare the intervention vs. the control (standard treatment, no treatment or placebo).
Keywords: intervention, treatment outcome, randomized controlled trial, pre-post study design, non-randomized controlled trials, quasi-experiments, evaluation studies, program evaluation, pre-test, post-test, effectiveness, etc.
PubMed/MeSH database (definition)
Healthknowledge.org.uk (basic outline of the design)
Biochemia-medica.com (description of the intervention design)
Correlational research attempts to determine if a relationship exists between two variables, and the degree of that relationship.
Keywords: correlation, statistical study, data correlation, data analysis
PubMed/MeSH database (definition)
Medical Dictionary (definition)
Raynor Memorial Libraries (description of various types of research)
Review article summarizes the findings of others studies or experiments; attempts to identify trends or draw broader conclusions. Scholarly in nature but not a primary source or research article, however its references to other articles will include primary sources or research articles.
Keywords: review, literature review
What's a review article? (definition and tips on how to find review articles)
How do I find these types of studies?
In most databases and indexes, you can limit your search to include only specific type of articles. Some databases might use the term "intervention" or "randomized controlled trial." Set up your search using your main concepts (for example diabetes AND "low income," then find the limit for "randomized controlled trial," select it, and run your search. You might add the word "intervention" to your search string, if you find too many results on your topic.
Search strategy examples:(1) If you open up PubMed, you can search for intervention articles on cancer AND "Asian Americans" AND intervention in the search bar, then clicking the SEARCH button. Look at the list of filters on the left-hand side of the page of search results. Under “Article Type” you’ll see a link labeled “Randomized Controlled Trial.”
(2) Run a similar search in Academic Search Complete and use "randomized controlled trials" instead of the keyword "intervention." Apply further limiters as shown below.
Examples of research articles
Wenrich, T., Brown, J.L., Wilson, R.T., & Lengerich, E.J. (2011). Impact of a community-based intervention on serving and intake of vegetables among low-income, rural Appalachian families. Journal of Nutrition Education and Behavior, 44(1). Retrieved from http://www.jneb.org/article/S1499-4046(11)00344-7/abstract.
Holt, C. L., Litaker, M. S., Scarinci, I. C., Debnam, K. J., McDavid, C., McNeal, S. F., ... & Martin, M. Y. (2012). Spiritually based intervention to increase colorectal cancer screening among African Americans screening and theory-based outcomes from a randomized trial. Health Education & Behavior. Retrieved from http://heb.sagepub.com/content/early/2012/09/28/1090198112459651.full.pdf+html
Bower, K. M., Thorpe, R. J., & LaVeist, T. A. (2013). Perceived racial discrimination and mental health in low-income, urban-dwelling Whites. International Journal Of Health Services, 43(2), 267-280. Retrieved from http://sfx.umd.edu/cp?sid=Entrez:PubMed&id=pmid:23821905
Bowie, J., Juon, H., Dubay, L., Lebrun, L., Curbow, B., Thorpe, R., & LaVeist, T. (2009). Cancer prevention behaviors in low-Income urban Whites: An understudied problem. Journal Of Urban Health, 86(6), 861-871. doi:10.1007/s11524-009-9391-2. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2791816/.
Thomas SB, Quinn S, Butler J, Fryer CS, Garza, MA. (2011) Fourth generation health disparities research: Accelerating innovations to achieve health equity. Annual Review Of Public Health, 32,411-12. Retrieved from http://www.annualreviews.org.proxy-um.researchport.umd.edu/doi/abs/10.1146/annurev-publhealth-031210-101136
Braveman, P., Egerter, S., & Williams, D. R. (2011). The social determinants of health: Coming of age. Annual Review Of Public Health, 32, 381-98. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21091195