Selecting articles to read from a results list is an art, not a science. Practicing makes it easier, which is why a literature review is a common assignment. Expect that you will be repeating the steps of searching and selecting articles several times; it is unlikely you will capture all needed materials in an initial search.
One possible method:
- Conduct a keyword search and locate a few somewhat-relevant looking articles
- Obtain the full text and read the articles.
- Consider: after reading these articles, which of my initial questions about this topic have been answered? What new or additional questions have I developed? Can I see any patterns or gaps starting to emerge in the literature? Use these new questions and patterns/gaps to help develop additional keywords to add to your search, to investigate another aspect of this topic.
- Repeat this process until you have answered your initial questions, answered new questions developed while reading, and can identify patterns/commonalities in the work, or can identify that there are few commonalities.
Do not expect to find any articles that cover your exact topic. Expect to find articles that explain or investigate one or two aspects of your topic. Your job as the reviewer is to find articles that cover all aspects of the topic and combine their findings into a cohesive literature review.
A common question about literature reviews is knowing when to stop searching for additional materials. How will you know you have enough? Consider whether you could answer the relevant questions below; if you can, you may be ready to move on to writing.
1. Has your topic been studied a lot (over 200 articles a year on this topic) or a little? Why is there a large amount or little amount of research? Is it the same every year, or are there variances in publishing rates?
2. How has it been investigated before-- using prospective or retrospective research methods; which techniques or laboratory procedures? What was measured and using what scales or procedures? Can you characterize the results of the prior investigations? Are they uniform or do they vary widely?
3. When was this topic studied, and do my selected articles represent relevant time frames? Where has this topic been studied, and do my selected articles represent relevant locations?
4. If the topic I am investigating can affect a lot of people-- do I have representative information about a variety of people? From a variety of geographic locations, races/ethnicies, ages, locations of living (community-dwelling vs. hospital inpatients), gender, disease stage, etc? If I don't-- is this because I didn't look, because no one has studied this topic in this group, or because the topic doesn't affect this group?
5. To whom is this topic important- microbiologists, patients, occupational therapists, genetic counselors, etc.? Do I have perspectives written by and for the groups that are important to my topic?
6. How does my research project fit into this existing research? Do I offer a new perspective; develop a new technique; replicate the results of a study; answer questions that other researchers developed; fill in gaps in knowledge; etc.?