What causes disease?
For any "disease" or condition, you could start by considering interactions among environmental and social factors.
» Poor diet, resulting from food choices, "causes" nutritional deficiency or obesity in a population
» Is it "caused" by historical distribution of land use, including (in developing countries) during colonial times?
» Or by the regulatory environment, including crop subsidies, food inspections, etc.?
» What about the role of NGOs, IGOs, aid networks?
» What about infrastructure, such as food distribution networks, transportation, etc.?
» Is the status of women/girls a factor?
» What about mental health issues?
» What is the role of commercial activity?
» What about the healthcare and health insurance system?
This "Planning your Literature Search" template (PDF; Univ. of Leicester) is a useful tool to help you plan your literature search.
This Literature Review Matrix (.doc) can help you organize what you find in your literature search.
(Revised from Health sciences literature review made easy: the matrix method, J. Garrard; Sudbury, MA: Jones and Bartlett Learning, 2011)
» You can adapt RefWorks, EndNote, Zotero, or Mendeley to be used with a matrix like this by using notes or custom fields in your database.
Nearly all the databases you use to find articles, etc., retain your search history for the duration of your session.
Literature reviews, like all research, should be rigorous and reproducible. Save or print your search history to help document your search strategy, which should include:
PubMed's History (click "Advanced" under the search box) and My NCBI can help with both saving your search strategy and the citations you find in PubMed. See the PubMed Tips guide for more information. Other databases have similar tools to save and/or download search history.