Be wary of claims that rely on a single peer-reviewed study. Note that the authors of this review article on the effectiveness of Botox for the treatment of migraine analyzed over 90 articles, 28 trials, and 4190 participants in order to make their determination. (You can find review articles like this one in the library's Cochrane Database of Systematic Reviews. A Cochrane review is a systematic review that attempts to identify, appraise and synthesize evidence to answer a specific research question. Researchers conducting systematic reviews use explicit, systematic methods aimed at minimizing bias, to produce reliable findings to inform decision-making.)
A single study, even with one participant, can be a valuable contribution to the scientific literature. But when assessing claims, value those that incorporate a variety of studies over those that rely on a single study. Think of your own Homeland Security research papers--would your professors be satisfied if your reference list consisted of a single source?
Occasionally, even the most prestigious journals publish flawed research. Take for example this infamous article from The Lancet, which suggested a link between the MMR vaccine and autism. After publication, a serious conflict of interest was exposed, as well as some unethical methods, and the article was retracted. Again, we should not be overly reliant on a single study.
"Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by library holdings or institutional repositories, but not controlled by commercial publishers, i.e., where publishing is not the primary activity of the producing body." (Schopfel, 2011)
Examples of grey literature producers:
Associations: Center for American and International Law, International Association for Counterterrorism and Security Professionals (policy papers, guidelines, reports)
Government: National, state, local (legislation, policy papers, congressional hearings, reports)
Educational Institutions: Naval Postgraduate School, universities, etc. (dissertations and theses)
Think Tanks: RAND Corporation, Atlantic Council, U.S. Army War College's Strategic Security Institute (reports, issue briefs, fact sheets)
You can find a wide range of grey literature from the sources above in the Homeland Security Digital Library:
Read and be prepared to discuss the following: What is the source of the piece of information? When was it published? Who are the authors? What type of information would you describe the piece as? What characteristics of the piece allowed you to make this determination?