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PH 293: Doctoral Seminar Library Resources: Starting a Literature Review


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Presented by Michael Sholinbeck (

Today's exercise set: DOCX  |  PDF

Before You Start: Your Topic, the Scope of Your Search, Where to Look

What causes disease? 

How you conceptualize your topic affects how you search for relevant information.

Consider first perhaps the interaction of environmental factors (eg, pollution, outbreaks) and social factors (eg, smoking, drug use). You may also wish to consider other aspects of your topic. 


  • Is exacerbation of asthma in West Oakland "caused" by air pollution and/or smoking? 
  • Or, is it "caused" by inadequate regulation of transportation, energy production, and/or tobacco? 
  • Or by historical racism in housing and neighborhood characteristics, including lax code enforcement? 
  • What about genetic factors? poverty? stress? 
  • What about access to appropriate prescription drugs? 

What is the wider context of your topic? Do some preliminary exploration, both in the literature and in discussions with your teachers, advisors, and peers. What are the relevant scientific and policy circumstances?

Always keep in mind the question you are trying to answer

What is the scope of your search? 

Literature searching always involves balancing finding all relevant citations (which means you may also find many non-relevant citations) with finding only relevant citations (which means you may miss some relevant citations).

The search scope, as well as the purpose and audience of your literature search, influences how you focus your search when using online databases, as well as when you decide you have "enough."

Remember that research is not a linear process; you may find yourself modifying your search terms as you explore your topic. However, if you are conducting a systematic review, you should have your inclusion/exclusion criteria set before you conduct your search.

Which disciplines are concerned with your topic? Which aspect(s) - legal, political, environmental, behavioral etc. - of your topic is/are of interest? 

Answering these questions will help you decide which databases to search for literature. Although PubMed may be the best place to start for most public health topics, you may miss key literature if you only search PubMed. 

The importance of indexing 

  • Do you want articles on labor (as in work) or articles on labor (as in giving birth)? (Or is it labour?) 
  • 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 (which is a finite list of terms); 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

Recommended Books

Critically Evaluating What You Find

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?
  • Significance of a single study: Science is an incremental process; one study rarely "changes everything"

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.

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.

» Take a look at a few citations (.doc) on the topics discussed above

Reliability and validity
Reliable data collection: relatively free from "measurement error:" 
» Is the survey written at a reading level too high for the people completing it? 
» If I measure something today, then measure it again tomorrow using the same scale, will it vary? Why? 
Validity refers to how well a measure assesses what it claims to measure: 
» If the survey is supposed to measure "quality of life," how is that concept defined? Is it measurable? 
(Adopted from Chapter 3, Conducting research literature reviews : from the Internet to paper, by Arlene Fink; Sage, 2010.)
Extensive discussions of reliability and validity are available in several texts, such as Textbook in Psychiatric Epidemiology (3rd Ed.; M. Tsuang et al. Wiley. 2011; See chapters 5 and 7).

What to consider when looking at survey or estimated data:

  • Look at sample sizes and survey response rates - representative of your population? Enough responses to be valid?
  • Who was surveyed? - representative of population being compared to? Include group you are interested in?
  • Were the survey respondents from heterogeneous groups? Do the survey questions have a similar meaning to members of different groups?
  • How was survey conducted? Via telephone? - Many people only have cell phones. Random selection or targeted group?
  • What assumptions and methods were used for extrapolating the data?
  • Look at definitions of characteristics - Does this match your own definitions?
  • When was the data collected?

Finding Previous Students' Dissertations

You may be interested in looking at previous students' dissertations

Many (perhaps most) UCB PhD dissertations are available online:
Use the Dissertations and Theses @ University of California database on our
Dissertations and Theses guide.
Enter the term Ph.D. in the search box, changing the drop down menu to Degree. (Important: Use the period dots: Ph.D.).
Limit to UCB dissertations by adding the word berkeley in the next search box, and select University/institution in the drop-down menu.

Add a 3rd row, then enter a topic term (eg, diabetes, epidemiology, causal inference, etc.); this will narrow the results to dissertations on your topic of interest.

To find SPH dissertations in the library using OskiCat or Melvyl, use the instructions here. Epidemiology PhD dissertations are easily located using OskiCat by entering "Thesis (Ph.D. in Epidemiology)" as a Keyword(s) search. Important: Use the "quotation marks."

Writing Science: How to Write Proposals that Get Funded and Papers that Get Cited

The National Center for Faculty Development & Diversity offers a webinar series on these topics.

First, create an account here: - UC Berkeley affiliates are eligible to create an account.

Then, click this link to enroll in the webinar series.


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