Before you can begin collecting articles, you must create search terms (that can be put into different databases) in order to retrieve all of the relevant articles pertaining to the meta-analysis. To begin, start by using broad search terms in order to get a feel for how many relevant articles there may be. Once you have created a set of broad search terms, you can begin to narrow the search. In order to narrow the search terms it is important to:
Put all phrases in quotation marks. Ex: “flow mediated dilation” or “physical activity”
Put a capitalized OR in between different variations of a word. Ex: fatigue OR energy Ex: glucose OR lipid OR fat
Put NOT before any search bar with phrases that the researcher specifically does not want to appear in the search results (this may or may not be necessary). Ex: NOT animal OR rat OR mouse
The last step to developing search terms is making sure that they work. In general, about half of the search results will be rejected and a meta-analysis requires there to be about 20 relevant articles in order to be considered sufficient. Therefore, the search terms should yield approximately 40 articles, or more. Once you have established your search terms, it is time to start collecting articles. Began this step by searching in databases such as Web of Science, PubMed, and PsycInfo rather than Google Scholar. The use of these databases will yield a more specific collection of studies that will be easier to work with. The process of collecting articles requires:
Application of knowledge of the question/field.
Everyone to have an understanding of any necessary procedures, measurements, etc.
An established set of exclusion criteria. It is crucial that everyone understand which studies can be accepted as well as which ones should be rejected. Be sure to take careful notes on established rejection criteria so that you can refer back to them when questionable articles appear.
Keep a careful list (preferably in Excel) of articles as you go through them. Remember that your goal is to collect all articles relevant to your field of interest, so recheck your searches regularly for new publications.
The Excel sheet should include the following information:
First author's last name
Study title
Study year
Search engine (ex. Web of Science, PubMed, etc.)
Article's number in the search
Status (referring to whether the article was accepted or rejected)
Reason for rejecting
It is also helpful to color-code the excel sheet, with rejected articles one color and accepted articles another color. HOWEVER. DO NOT REJECT ARTICLES IN THIS INITIAL PHASE OF COLLECTING UNLESS YOU ARE 100% SURE THEY DO NOT MEET THE INCLUSION CRITERIA.
