PH 251C: Causal Inference and Meta-Analysis in Epidemiology: Library Research & Evaluation

Is your topic researchable? 

• "Harmful fetal effects of beer consumption by pregnant students at college athletic events" 
• "Determinants of binge drinking among female college students in the United States" 
• "Alcohol consumption by young adults"

Think about your topic

• What terms encapsulate your topic?
• Are there synonyms?
• What fields of inquiry are relevant: psychology? law/policy? education? anthropology?

Let's talk about indexing! 

• Do you want articles on labor or articles on labor? Or is it labour? 
• Do you want articles on HIV (a virus) or articles on HIV diseases (such as AIDS)? 
•  Is epidemiology a concept relating to the causes and distribution of diseases, or is it what epidemiologists do? 
•  Is lead a noun or a verb?

Indexing facilitates more precise search statements, especially for topics that are vague or ambiguous.

• Using index terms also helps you avoid the need to think of every possible synonym or alternate spelling of your search terms.
• Indexing means the citations in the database are assigned terms from a controlled vocabulary (Not all databases use a controlled vocabulary, however)
• Index terms are sometimes called descriptors or thesaurus terms; in PubMed they are called Medical Subject Headings, or MeSH

What is evidence?
All research is (potentially) "evidence" and there are no "perfect" studies. 
Critically evaluating what you read will help any unearth biases or methodological shortcomings that may be present.

Is there an agenda (bias)?
It's doubtful that any study of humans is without some kind of bias, either in the study design, or in the author's pre-existing beliefs. How bias in methodology was controlled and the significance of bias in any particular study is what's relevant. 

Things to consider:

• The question being addressed: What kind of research gets funded?
• Publication bias: Research that shows no effect tends not to get published
• Conflict of interest, author affiliation, source(s) of funding: Does the researcher (or the funder) have a vested interest in the outcome?
• Documentation and assumptions: Are all stated "facts" referenced?
• Peer review: Is the article peer-reviewed? Does it matter?
• Authority: Does the researcher have the knowledge to work in this area?

Who pays for science? Does it matter?  (There is evidence that it does matter)
Research may be funded by:

• Government
• Industry/trade groups
• Private foundations/associations
• etc.

This article (PDF) discusses the "manufactured uncertainty" created by industry groups that sponsor research and publishing on chemicals.

» Take a look at a few citations (.doc) on these topics

Things to keep in mind:

• All research is (potentially) "evidence" and there are no "perfect" studies.
• Is there an agenda (bias)? 
  • It's doubtful that any study of humans is totally without some kind of bias, either in the study design, or in the author's pre-existing beliefs, not to mention the source of the research funds. How bias in methodology was controlled and the significance of bias in any particular study is what's relevant.
• Is qualitative research "evidence"? 
  • If your goal is to understand beliefs and meanings in the group with whom you are working, then qualitative studies can be important.

The Literature Review Matrix (below) may help you organize what you find in your literature search. This matrix is a simplified version from Health Sciences Literature Review Made Easy (various editions of this book are available at several UCB libraries).

Nearly all the databases you use to find articles, etc., retain your search history. Literature reviews, like epidemiological research, should be rigorous and reproducible. Save or print your search history to help document your search strategy, which will include:

• the date of the search(es),
• search terms used (keywords; title words; MeSHs, thesaurus terms, descriptors),
• any limits (eg, language, publication dates) that you placed on your search.
• how many relevant citations you found in each database.

Using PubMed's Clipboard and My NCBI can help with both saving your search strategy and the citations you find.
More information may be found on the PubMed Save Citations tab of this guide.

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