This key stage in a research synthesis includes...
Coding and data extraction
Any time you search in multiple databases, there will be duplicate results. There are many different approaches and tools for removing duplicates (de-depulication), and they all have their pros and cons. No matter which approach you choose, keep track of result totals before and after deduplication in your PRISMA diagram!
Once results have been deduplicated, you will begin the screening process. This is where you'll apply your eligibility criteria to each result. While strict systematic review methodology requires all eligibility criteria to be defined a priori (in advance), some research synthesis approaches allow for ad hoc (as you go) criteria based on the researchers' increasing familiarity with the available research. Just be sure to document if your approach shifts!
Screening often happens in two steps.
Some reviews, particularly in medicine, require a critical appraisal or a risk of bias assessment for each study that makes it through the screening process. For any review, it's important to consider the impact that poorly designed studies could have on your findings and to rule out inaccurate or biased work.
Key resources:
Researchers typically develop a coding schema to outline the data points that will be collected and synthesized from each study included in the review. This often includes things like participant demographics, sample sizes, interventions, methods, outcomes and more. Most often, data is collected in some type of form, table or spreadsheet.
Key resources:
From Cochrane Handbook:
From Collaboration for Environmental Evidence Guidelines:
This work is licensed under a Creative Commons Attribution-NonCommercial 2.0 Generic License.