At the end of the screening process and any subsequent citation searching, you will have a final list of papers that will be included in your systematic literature review and you can begin analysing your results.
There are two main components you will need to consider:
How many people do I need to complete the risk of bias assessment and data extraction?
For published systematic reviews, the risk of bias assessment and the data extraction of each paper needs to be done by at least two people. For master's projects, it is common for students to do this alone.
Check your course handbook and speak to your supervisor about what is expected of you.
Assessing your included papers for risk of bias can help you determine how much weight you should place upon the findings of each paper.
How do you conduct a risk of bias assessment?
There are a number of tools that you can use to conduct a risk of bias assessment. The most commonly used are:
For a systematic literature review you may not need to undertake a full risk of bias assessment using a tool on your included papers, but you should still read the paper critically and form a judgement about how trustworthy the study and its findings are.
In the context of a systematic literature review, your 'data' is information in the papers that meet your inclusion criteria. This might be information about; the study design, the participants, the intervention or exposure, the results, etc... This information is extracted from each paper to make it easier to compare and synthesise the data.
You do not need to extract everything, just the information that is relevant to your research question. If you are writing a narrative synthesis the data extraction may be descriptive and aimed at providing an overview of the study. If you are conducting a meta-analysis you may also need to collect more granular data.
Data extraction is usually done with a form or a table. You should design your data extraction form or table around the information you need to help you answer your research question. Covidence has inbuilt tools to help you create a data extraction form, and fill this in for each study, but there is no obligation to use these. You may find it easier to set up your own document or spreadsheet to complete data extraction.
How to read a paper: The basics of evidence-based healthcare
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