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September 20, 2012
CONDUCTING A SYSTEMATIC REVIEW:DEFINING A PROBLEM LITERATURE REVIEW
Stages of Systematic Review
1. Define the Problem2. Literature Search3. Data Evaluation4. Data Analysis5. Interpretation of Results6. Presentation of Results
Define the Problem
What research evidence will be relevant to the problem or hypothesis of interest in the review?
• Define variables of interest• Define how variables are related (can be a
hypothesis)• Define search criteria
Define the Problem:Defining Variables
Conceptual vs Operational• Conceptual – describes qualities of the
variable in general or qualitative terms• Example: Intelligence – “a capacity for learning,
reasoning, understanding, and similar forms of mental activity”
• Operational – describes observable events used to measure the variable
• Example: Intelligence – Intelligence Quotient (IQ) score
Defining Variables:Primary research vs systematic review
•Primary research: conceptional and operational definitions must be precisely defined before experiment
•Systematic review: can begin with a broad conceptual definition and known operational measures and further define during course of review
Define the Problem:Relationship between variables
•How do the conceptual and operational definitions fit together in the literature?•Are there multiple operational definitions for one conceptual variable?•Example: intelligence may be measured by many tests (IQ, ACT, SAT, GRE)
Define the Problem:Determine Appropriate Research Designs
1. Should the results of the research be expressed in numbers or narrative?
2. Is the problem or hypothesis seeking to uncover a description of an event, an association between events, or an explanation of an event?
3. Does the problem or hypothesis seek to understand how a process unfolds within an individual unit over time, or what is associated with or explains variation between units or groups of units?
•Descriptive: ask what is happening•Measurement or description of characteristics of an event• Example: reporting of mean IQ score in Tufts freshmen
•Associations: what events happen together•Measurement of a correlation• Example: is IQ score in Tufts freshmen associated with major?
•Explanations: explain why an event happens• Construction of a predictive model• Example: modeling predictive factors in IQ score in Tufts freshmen
Define the Problem:Determine Appropriate Research Designs
Literature SearchWhat procedures should be used to find relevant research?
• Identify sources for research• Identify search terms used
Literature Search:Sources and Search Methods
•Reference databases (pubmed, etc)•Footnote chasing•Consultation with colleagues•Library browsing•Citation searches
Literature Search: Search Terms
•Begin search with broad conceptual definitions as search terms•Want to identify largest number of potentially relevant articles
•Narrow search using operational definitions later• If you find numerous operational definitions in initial search•Which operational definitions to include?
•Example: using term intelligence instead of searching for IQ, SAT, GRE
•Develop exhaustive list of terms used for conceptual definition •Consider different levels of a term: scientific vs lay person•Consider synonyms•Consider spelling in different countries (estrus vs oestrus)•Terms vary by source•Examples?
Literature Search: Search Terms
Logic Models
A systematic, visual representation of a plan
Logic Model for Systematic Review
Input Activities Outputs Outcom
e Impact
Based on definition of problem: VariablesSearch terms
Literature search
Data evaluation
Data analysis
Quantitative or qualitative results of review
Conclusions
Resolve conflict
New information for field
Drive new research
Change in policy
Questions on Articles for Discussion1. How do the authors define the research
problem?2. What variable(s) are defined in the review?a. Conceptual definitionb. Operational definitionc. Effect vs outome
3. Describe the review’s search methodologya. Search terms – exhaustive?b. Sources of information for reviewc. Study eligibility – types of studies included