Fundamentals of Study Design Lauren Duke MA Program Coordinator MeharryVanderbilt Alliance 17 July 2015 Session Outline Research Question Type of Study Observational Experimental Quasiexperimental ID: 760266
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Slide1
Principles of Research Writing & Design Educational SeriesFundamentals of Study Design
Lauren Duke, MA
Program Coordinator
Meharry-Vanderbilt Alliance
17 July 2015
Slide2Session Outline
Research Question
Type of Study
Observational
Experimental
Quasi-experimental
Study Designs
Cross-sectional
Studies
Cohort Studies
Case Control Studies
Randomized
Controlled Trial (RCT
)
Case-
series
Case Report
Slide3What do you want to know?
Cause and effect? Prevalence? Incidence?
Example:
W
hat a child watches on television and violent behavior
Is this your first study with this population?
Is it feasible?
Money
Time
Rare outcomes
Infrastructure
How many participants do you have access to?
Slide4What do you want to know?
Predictor vs. Outcome variables
Violent Behavior
Television Program
Slide5All Studies
Experimental
Observational
Randomized Control Trial
Non-randomized
Analytic
Descriptive
Case series
Case reports
Cohort Study
Cross Sectional
Case-Control Study
Quasi-experimental
Slide6Observational Analytic Study Designs
Slide7Cross Sectional Studies
Can be used to examine associations between two or more variablesPrevalence
Slide8Cross Sectional Studies
Serial SurveysUsing cross sectional studies in the same population over certain time intervals
Slide9Cohort Studies
Prospective and RetrospectiveIncidenceThe proportion who develop a disease or condition over time. Outcome has not yet occurred
Prospective cohort study begins here
Retrospective cohort study begins here
Slide10Multiple-Cohort Studies
Two or more separate samples of subjectsOne group with exposure to a potential risk factor, one withoutLevels of exposure
Exposure
Outcome
Control
Outcome
Slide11Design
Advantages
Disadvantages
Cross-sectional
- Short duration
- Potential first step for a cohort study or clinical
trial
- Yields prevalence of multiple predictors and outcomes
- Does not establish sequence of
events
- Not feasible for rare predictors or rare outcomes
- Does not yield incidence
Cohort Designs
All
- Sequence
of events
- Multiple predictors & outcomes
- Number of outcomes grow over time
- Yields incidence
- Often requires large sample sizes
- Less
feasible for rare outcomes
- Attrition
Prospective
- More control over participant selection
& measurements
- Avoids bias in measuring predictors
- Follow-up can be lengthy
- Often
expensive
Retrospective
- Data collection complete
- Relatively inexpensive
- Less control over participant
selection
& measurements
Multiple cohort
- Useful
for
distinct
cohorts with different or rare exposures
- Bias and confounding from sampling distinct populations
Slide12Case-Control Studies
“Working backwards” or RetrospectiveEffect studied first, Cause secondEx. Infant sleepingposition and SIDS
Slide13DesignAdvantagesDisadvantagesCase-Control- Useful for rare outcomes- Short duration, small sample size- Relatively inexpensive- Bias & confounding from sampling two populations- Limited to one outcome variable- Sequence of events may be unclear- Does not yield prevalence or incidence
Case-Control Studies
Slide14Slide15Observational Descriptive Study Designs
Slide16Case-series Studies
Descriptive, not analyticNot hypothesis drivenSmaller sample sizeSpecific populationTracks participants with known exposure, potentially based on similar treatment, and examines medical records for outcome.
Follow-up
Slide17Case-Report Study
A detailed report of the of an individual patientSymptomsSignsDiagnosisTreatmentFollow-up
Treatment
Follow up
Diagnosis
Symptoms
Slide18Experimental Study Designs
Slide19Randomized Clinical Trial (RCT)
Parallel, between-groups designCan have more than two groupsInvestigator assigns treatmentRandom assignmentParticipants are blind to group assignmentDouble-blind studiesGold Standard
Slide20Quasi-experimental Design
Same as RCT, with no random assignmentTreatment with or without control groupEffect of a specific intervention on a specific populationGroups may already be definedInvestigators may designate cutoffs for treatment vs. controlPre-test Post-test designPractice effects
Slide21All Studies
Experimental
Observational
Randomized Control Trial
Non-randomized
Analytic
Descriptive
Case series
Case reports
Cohort Study
Cross Sectional
Case-Control Study
Quasi-experimental
Slide22Supplemental Resources
Slide23Please complete evaluation forms prior to leaving- Thanks!
Slide24Session Schedule
All sessions held at the MVA from 12pm-1pm Date Topic June 19Literature Reviews & Grants 101June 26Writing a Scientific Manuscript (Part 1)July 10Writing a Scientific Manuscript (Part 2)July 17Fundamentals of Study Design July 24Fundamentals of Biostatistics (Part 1)July 31Fundamentals of Biostatics (Part 2)
To RSVP call (615) 963-2820 or email
mva@Meharry-Vanderbilt.org