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Evidence Synthesis & Systematic Review Research

This guide provides an introduction to evidence synthesis research methods.

Consult with an OSU Librarian regarding exploratory searching

While OSU Libraries does not offer an evidence synthesis search service at this time, talking with a librarian for your college or program about your research question can help you be more efficient when

1) choosing what databases/search tools to use for your exploratory searches, and

2) figuring out relevant exploratory search terms.

 

Before scheduling a consult, it will help your librarian to know what your research question currently is (even if it is not yet finalized) so provide that information to them before you meet.

Why do an exploratory search?

flow chart of the interative search process Once you have an initial research question, you can develop and refine your research question and eligibility criteria  through exploratory  searching. Exploratory searching is also called preliminary, initial, and naive or novice searching. Regardless of what you call it, it is simply a series of searches conducted prior to starting the review with the goal of producing a well-defined scope with clear demonstration of contribution to the field. This is an iterative process as illustrated in the image to the right. 

Throughout the exploratory search you should collect existing and in-progress reviews and seminal articles related to your scope. Ultimately, this phase should help your team produce

  • A clear, well-defined scope 
  • 2-5 seminal articles to validate your search later on 
  • Context of what has been done to address this question, illustrating that this review does not duplicate existing or in-progress publications

At the bottom of this page, take a look at where to start exploratory searching.

 

Credit: "Exploratory Search" (Virginia Tech University Libraries) adopted by OSU Libraries & Press under CC BY-NC-SA 4.0.

Where to exploratory search?

General Searches

In short, where you do exploratory searches will depend on your research question. In other words, you should consider searching wherever you are likely to find material that answers your research question.


Databases

Search academic journal databases that may be relevant to your topic. Consider your topic from perspectives other than your own discipline - it's likely your topic overlaps with several disciplines. For example, if you are examining a public health topic, it may be useful to search databases related to health / medicine and social sciences.

You can also use this exploratory phase to determine whether a database is relevant and should be searched as part of your final comprehensive systematic review search strategy, or not.

 

Check out the OSU Libraries "A-Z Database List", or Librarian-curated Library Guides related to your discipline!

Hint: Sort "By Subject" to find relevant guides

 


 

More places to search...

The possibilities of where to exploratory search are endless! Consider searching anywhere that seminal articles or existing/in-progress reviews relevant to your scope may exist. Here are a few more places to get you started.


General Purpose Repositories

Researchers use these sites to share unpublished or in-progress research and reviews, procedural documentation, and other grey literature. For example:


Repositories that contain Preprints

Researchers uses these sites to openly share research, some of which is not yet published (or peer-reviewed), also called 'preprints'. For example: 


SR-Specific Repositories

There are several systematic review repositories that exist - some contain only published reviews, while others include review registrations and protocols. In the following table, we present and link out to some repositories that specifically house systematic reviews and similar evidence synthesis publications.

"...all registered titles for systematic reviews or evidence and gap maps that have been accepted by the Editor of a Campbell Coordinating Group. When titles progress to protocol stage, the protocol is published in the Campbell Systematic Reviews journal."

Both registry and journal include topics related to Business and Management, Climate Solutions, Crime and Justice, Disability, Education, International Development, Knowledge Translation and Implementation, and Social Welfare

"...the leading journal and database for systematic reviews in health care. CDSR includes Cochrane Reviews (systematic reviews) and protocols for Cochrane Reviews as well as editorials and supplements."

"Cochrane Collaboration produces high-quality systematic reviews in health disciplines. For more detail and specific fields of research, check out the Cochrane Review Groups and Networks."

"...focussed coverage of systematic and non-systematic reviews of effectiveness in health promotion and public health worldwide. This register currently contains details of over 6,000 reviews of health promotion and public health effectiveness."

"...a collaborative, multilingual database of health evidence. It is the largest source of systematic reviews relevant for health-decision making, and a large source of other types of scientific evidence."

"...quality-rated systematic reviews evaluating the effectiveness and cost-effectiveness of public health interventions, including cost data."

"...a collection of world-class resources driven by the needs of health professionals and consumers worldwide"

"International database of prospectively registered systematic reviews in health and social care, welfare, public health, education, crime, justice, and international development, where there is a health related outcome."


Web Browsing

While Web browsing in Google Scholar (or Google) is a great place to start exploratory searching, remember that results are tailored to individual users, are not replicable, and algorithms are not transparent. Therefore never rely only on web browsing for your exploratory searching and especially for your comprehensive searching.

 

Credit: "Where to "Exploratory Search"? (Virginia Tech University Libraries), used by OSU LIbraries & Press  under CC BY-NC-SA 4.0.

Exploratory search tips

Searching tips

In academic journal databases, you can sometimes find a filter for Systematic Reviews, Meta-Analyses, and/or simply Reviews. If a built-in filter doesn't exist, you can add the term "review" to your search.

Initial Research Question: Does drinking coffee reduce the likelihood of falling asleep while driving?

(coffee) AND (sleep) AND (driving) AND (review)

 

If you get too many results, you can specify the kind of review:

(coffee) AND (sleep) AND (driving) AND ("systematic review" OR "meta analysis")

 

 

Credit: "Existing & in-progress reviews: Searching Tips"" (Virginia Tech University Libraries) adopted by OSU Libraries & Press under CC BY-NC-SA 4.0

What if my review already exists?

Evidence synthesis projects are pursued to answer a research question. If a published project already answers your question, the existing review can be the foundation of your next research project!


Pursuing a different review

Sometimes it is still important to pursue a review, even if your original research question(s) have been answered. What is considered "the same" review is not always clear. Generally speaking, you need to justify that and illustrate how your new review contributes something unique to the field. 

If a review already answers your question, and your team would still like to pursue a review, your team can:

  • Update reviews that are out of date
  • Enhance reviews with significant limitations / quality concerns
  • Attempt to replicate the review 
  • Revise your original question 
 

Credit: "Existing & in-progress reviews: About" & "Existing & in-progress reviews: What if my review exists?""  (Virginia Tech University Libraries) adopted by OSU Libraries & Press under CC BY-NC-SA 4.0.

Seminal articles

What is 'Seminal Work'?

In general, seminal work, also called pivotal, landmark, or seed studies, are articles that are central to the research topic and have great importance and influence within the discipline. Seminal articles are likely to be cited frequently in different journal articles, books, dissertations etc. 


Seminal Articles in Systematic Reviews

In systematic reviews and/or meta-analyses, seminal work are the "seed articles" for your specific review - the articles (or other material) you know need to be included in your final synthesis. These articles may have sparked the team's interest in pursuing a review or may be identified through the exploratory search.

 

Identifying Seminal Articles

As seminal articles are often cited more frequently than other articles, some search tools offer options to sort search results by the number of citing references or to at least view the number of or link to a list of citing references. A few examples are offered:

  • Web of Science (all disciplines represented): can sort results list by "Citations highest first"
  • PsycInfo (psychology): can sort results list by "Times Cited"

 

  • Google Scholar (all disciplines represented): can view "Cited by" count under each record in the results list
  • PubMed (biomedicine): can click on "Cited by" link in each individual record to get to the list of citing articles in PubMed (but it doesn't provide the total citation count as a number)
  • Sociological Abstracts (sociology/social work/social sciences): can view "Times cited" count for each record in the results list

 

Credit: "Seminal Articles" (Virginia Tech University Libraries)  adapted by OSU Libraries & Press under CC BY-NC-SA 4.0.