PsyD Systematic Reviews

What Are Eligibility Criteria?

Eligibility criteria (also called inclusion and exclusion criteria) define which studies will be included or left out of your systematic review.

They help make your review focused, clear, and consistent—and ensure you’re only including studies that truly help answer your research question.

Why Are Eligibility Criteria Important?

• Keep your review systematic and objective

• Prevent bias by deciding on your criteria before you start screening

• Make it easier to explain why each study was included or excluded

What Might Eligibility Criteria Include?

• Population: What age, group, or condition are you focusing on?

• Intervention or exposure: What treatment, condition, or variable?

• Comparison: Are you comparing it to something else?

• Outcomes: What are you measuring (e.g., anxiety reduction, test scores)?

• Study design: Only RCTs? Qualitative studies? Mixed methods?

• Date range or language: Do you want only recent studies? Only English?

• Tip: Use your framework (like PICO, SPIDER, or SPICE) to help shape your criteria!

Keywords vs. Eligibility Criteria: What’s the Difference?

Understanding the difference helps you build a better search and screen studies more effectively.

From University of Melbourne Library LibGuide

The Importance of a Search Methodology

The goal of systematic review searches is to identify all relevant studies on a topic, so a clear methodology for finding studies is an essential element. Your approach needs to be well documented (transparent) and as replicable as possible.

Important Elements of a Search    

• Work with a GSEP librarian
• All major concepts are included in the strategy; typically, we do not search on the outcomes.
• Use of all appropriate controlled vocabulary terms across each database.
• Appropriate use of explosion, subheadings, and floating subheadings.
• Use of natural language (text words) in addition to controlled vocabulary terms.
• Use of appropriate synonyms, acronyms, etc.
• Truncation and spelling variation as appropriate.
• Appropriate use of limits and filters.
• Boolean operators used appropriately.
• Check indexing of exemplar articles.
• Search strategy adapted as needed for multiple databases (three minimum).
• Inclusion of grey literature sources - see below for more information. 

Watch the clip below to see how to properly perform and document a systematic search. 

What is Grey Literature? 

Grey literature refers to research and information that is produced outside of traditional academic publishing channels and is often not indexed in standard databases.

Examples include:

• Theses and dissertations

• Conference papers or posters

• Government or NGO reports

• Clinical trial registries

• Policy documents

• Preprints (a preprint is a version of a research paper that is shared publicly before it has been peer-reviewed or published in a scholarly journal)

Why is Grey Literature Important for Systematic Reviews?

• Reduces publication bias – Studies with negative or inconclusive results are less likely to be published in journals, but may exist in grey literature.

• Provides unique data – Some important studies (e.g., large government-funded reports) are only available in grey literature.

• Strengthens comprehensiveness – Systematic reviews aim to capture all relevant evidence, not just what appears in journals.

• Improves transparency – Shows readers you looked beyond the “easy-to-find” sources.

• Grey literature searching can be more challenging. It often requires using specialized repositories, trial registries, or even reaching out to researchers directly.

Common Grey Literature Sources: 

What is Data Extraction?

Data extraction is the process of pulling out the important information from each study you include in your systematic review.
It’s a key step that happens after you’ve finished screening your studies and finalized your inclusion list.

The goal is to collect the same types of information from each study so you can compare and analyze them later.

Why is Data Extraction Important? 

• Keeps your review systematic – everyone collects the same data in the same way

• Makes analysis possible – you can only compare studies if you have consistent details

• Reduces errors – structured forms help avoid missing key points

• Improves transparency – others can see exactly what was taken from each study

What Information Should You Extract? 

Remember to use your PICO, SPIDER, or SPICE framework to guide what to collect.

How to Extract the Data

1. Set up your extraction form on Covidence 
2. Pilot test the form – Try it on 2–3 studies and make adjustments
3. Double-check with a second reviewer – In systematic reviews, two people usually extract data independently and compare results
4.  Record Exact Data – Copy numbers and wording accurately before summarizing. Consistency is key!  
5. Document everything – Note decisions you make along the way

Tips for Success 

• Be consistent: decide up front how you’ll record numbers, units, and outcomes

• If something’s unclear in a study, note it rather than making assumptions

• Keep your raw extracted data safe—it’s your evidence for later synthesis

• Use clear labels: future you will thank you!

A librarian can help you brainstorm, write, and perform the search strategy. This is the stage of a systematic review where consultation with a librarian is arguably most valuable. We have extensive experience with the databases most often used in reviews. We know what they cover (and miss) and how they vary. Through conversation and exploratory searching, librarians can help you find the right balance between search sensitivity and specificity, and we can assist in finalizing a valid search protocol.