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Systematic Review Resources: Deduplication

Workshop Recording

De-duplication Introduction

Deduplication is the process of removing duplicate records from search results when multiple databases are searched. Duplicate records happen when the search results from the multiple databases are searched are combined into one file. A reference management system, such as Endnote, is used along with a methodology to remove those duplicate records. Deduplication is done prior to screening.

De-duplication Steps and Methods

  1. Download search results from all databases in RIS or XML format upon the completion of a database search.

  2. Select the file format recommended by the reference management tool or screening tool being used (RIS format is the most likely format).

  3. Decide on de-duplication method

    1. Use screening tool's built in algorithm (most screening tools will identify duplicates and ask you to screen them). Recommended for lower numbers of results 1-1000.

    2. The McGill Method (an adapted adapted version of an early version of the Bramer Method): Requires the use of Endnote. Recommended for results over 1000 records. 

    3. The Bramer Method. This is a complex method that requires the use of Endnote, it catches most, if not all duplicates and can save time if you have a high number of articles. See these videos for a demonstration of how the method is applied. Recommended for results over 1000 records

  4. De-duplicate results with selected method

  5. Import de-duplicated results into screening tool (i.e. Covidence, Rayyan, DeStillerDR,...)

  6. Record all information into spreadsheet or other tool regarding import of records and deduplication

De-duplication How-To-Videos

How to videos are in production, please check back soon.