When searching within the library databases you will come in contact with many different types of publications. The three main types of publications you will come across during your research are from popular, scholarly, and trade publications. For the majority of your work you will probably be searching for those "scholarly" or "peer-reviewed" sources.
Do keep in mind that even though a research article has been published in a peer-reviewed journal does not mean that the research performed was perfect. There are many factors to consider when evaluating an article to use in your research. Things such as: population characteristics, sample size, study design, funding for the study, author bias, currency of the information, etc., should all be taken into consideration when reviewing an article. Additionally, other publications such as editorials and book reviews can also appear in peer-reviewed journals but do not go under the same review process as the peer-reviewed journal articles.
Below you will find information to help you in the evaluation process.
Peer reviewed articles are research articles that have been evaluated and approved by other experts in the field before being accepted for publication in a journal.
While several databases give you the option to choose a checkbox to "limit to articles from peer-reviewed publications," these checkboxes are not fool proof.
Check Ulrichsweb you're not sure if a journal is peer-reviewed. Just look for the referee jersey next to the journal title.
Not all scientific studies are created equal. Analyzing a study's design can help you determine the strength and quality of evidence that a study holds. Below is what we often refer to as the "Evidence Pyramid". It is used to illustrate the evolution of the literature and depicts the levels of evidence provided by different types of studies.
Below you will find additional information regarding each of the study designs from the pyramid above. More information regarding finding "evidence-based" articles can be found on the evidence-based resources tab.
Case series and Case reports consist of collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups to compare outcomes, they have little statistical validity.
Case control studies are studies in which patients who already have a specific condition are compared with people who do not have the condition. The researcher looks back to identify factors or exposures that might be associated with the illness. They often rely on medical records and patient recall for data collection. These types of studies are often less reliable than randomized controlled trials and cohort studies because showing a statistical relationship does not mean than one factor necessarily caused the other.
Cohort studies identify a group of patients who are already taking a particular treatment or have an exposure, follow them forward over time, and then compare their outcomes with a similar group that has not been affected by the treatment or exposure being studied. Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.
Randomized controlled clinical trials are carefully planned experiments that introduce a treatment or exposure to study its effect on real patients. They include methodologies that reduce the potential for bias (randomization and blinding) and that allow for comparison between intervention groups and control (no intervention) groups. A randomized controlled trial is a planned experiment and can provide sound evidence of cause and effect.
Systematic Reviews focus on a clinical topic and answer a specific question. An extensive literature search is conducted to identify studies with sound methodology. The studies are reviewed, assessed for quality, and the results summarized according to the predetermined criteria of the review question.
A Meta-analysis will thoroughly examine a number of valid studies on a topic and mathematically combine the results using accepted statistical methodology to report the results as if it were one large study.