Literature Review Basics

First, let's be perfectly clear about what synthesizing your research isn't:

• - It isn't just summarizing the material you read
• - It isn't generating a collection of annotations or comments (like an annotated bibliography)
• - It isn't compiling a report on every single thing ever written in relation to your topic

When you synthesize your research, your job is to help your reader understand the current state of the conversation on your topic, relative to your research question. That may include doing the following:

• - Selecting and using representative work on the topic
• - Identifying and discussing trends in published data or results
• - Identifying and explaining the impact of common features (study populations, interventions, etc.) that appear frequently in the literature
• - Explaining controversies, disputes, or central issues in the literature that are relevant to your research question
• - Identifying gaps in the literature, where more research is needed
• - Establishing the discussion to which your own research contributes and demonstrating the value of your contribution

Essentially, you're telling your reader where they are (and where you are) in the scholarly conversation about your project.

Synthesis, step by step

This is what you need to do before you write your review.

1. Identify and clearly describe your research question (you may find the Formulating PICOT Questions table at the Additional Resources tab helpful).
2. Collect sources relevant to your research question.
3. Organize and describe the sources you've found -- your job is to identify what types of sources you've collected (reviews, clinical trials, etc.), identify their purpose (what are they measuring, testing, or trying to discover?), determine the level of evidence they represent (see the Levels of Evidence table at the Additional Resources tab), and briefly explain their major findings. Use a Research Table to document this step.
4. Study the information you've put in your Research Table and examine your collected sources, looking for similarities and differences. Pay particular attention to populations,  methods (especially relative to levels of evidence), and findings.
5. Analyze what you learn in (4) using a tool like a Synthesis Table. Your goal is to identify relevant themes, trends, gaps, and issues in the research.  Your literature review will collect the results of this analysis and explain them in relation to your research question.

Analysis tips

• - Sometimes, what you don't find in the literature is as important as what you do find -- look for questions that the existing research hasn't answered yet.
• - If any of the sources you've collected refer to or respond to each other, keep an eye on how they're related -- it may provide a clue as to whether or not study results have been successfully replicated.
• - Sorting your collected sources by level of evidence can provide valuable insight into how a particular topic has been covered, and it may help you to identify gaps worth addressing in your own work.