PH 293: Doctoral Seminar Library Resources: Start a Literature Search

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. 

Example:

• 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.

  ...Consider that how issues are framed is influenced by our assumptions and biases, and also, keep swimming upstream!

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

Below are some examples of questions or lines of inquiry.
Considering what question a research article addresses may help you determine if it is relevant to your needs:

• Are their racial or ethnic disparities in type 1 diabetes mellitus prevalence?
• Compare and contrast personal versus "upstream" factors relevant to these disparities.
• Describe examples of things that could reduce these disparities, differentiating between personal and upstream factors. 
• If a policy or program increases disparities, what are possible reasons for this? Differentiate between personal and systemic factors.
• Describe a plan/program/policy to reduce these disparities.
• Justify why systemic or upstream factors contribute more to these disparities than personal factors.

What is a good Research Question? It is a question that:

• identifies a relevant issue in your field;
• pursues relatively uncharted research territories to address the problem;
• piques the interest of others.

This blog post has tips on how to write a good research question, including examples of bad, good, and great questions.

To reduce bias, it may be best to pose your question in a neutral manner. Examples:

• Neutral question: What is the impact of school-based physical activity interventions on time spent engaged in moderate to vigorous physical activity among children, in comparison to children not exposed to school-based interventions?
• Non-neutral question: Which school-based interventions are effective in increasing the amount of time children engage in moderate to vigorous physical activity?

What is the question being addressed in the study you are reading? Compare:

• "Our intervention worked toward fixing Problem X."
• "The most effective interventions for fixing Problem X are: ..."
• "The effects of our intervention on Problem X are: ..."

When you read an article, answer (briefly) the following (source):

• What question are the authors addressing?
• What did they do to answer the question?
• What was their rationale for doing what they did to address their question?
• What were the findings?
• How were the authors think their findings mean?

Finding a systematic review that addresses the question you are interested in can be very helpful: take a look at the search strategy and databases used in the systematic review for tips on your search.

It may be useful to have a structure to help guide you when searching. 

When you formulate a research question, consider these elements:

• Phenomenon: What happened?
• Subject or Population: Who did it?
• Time: When did it happen?
• Location: Where did it happen?
• Cause or Motivation: Why did it happen?
• Process: How did it happen?

Note: It is possible that not all of the above elements will be appropriate for your search topic.
This worksheet (docx) will take you through the process of formulating a search.

PICO is another popular way to structure a search.
PICO stands for:

• Patient or Population;
• Intervention;
• Comparison or Control;
• Outcome.

Worksheet: Developing an Efficient Search Strategy Using PICO (docx): A  fillable form that provides a PICO example and prompts you to document synonyms and MeSH headings.

Embase has a PICO search form to guide you.

SPIDER is a search structure used in qualitative research. SPIDER stands for:

• Sample;
• Phenomenon of Interest;
• Design;
• Evaluation;
• Research Type.

Once you have a search strategy, you can try the Polyglot Search tool, which helps to translate a PubMed search into the correct syntax for several other databases, including Embase, Scopus, Web of Science, and more.

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
• Bias in randomized trial participation: there is evidence of racial bias in trial exclusion
• Conflict of interest, author affiliation, source(s) of funding: Does the researcher (or the funder) have a vested interest in the outcome? Many authors do not disclose industry payments.
• 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.

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?

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 UC Library Search, use the instructions here.

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

First, create an account here: https://www.facultydiversity.org/ - UC Berkeley affiliates are eligible to create an account.

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