ClinicalDesignTree - Reduced by: • Using objective,...

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Intro to Clinical Research JM Gay, DVM PhD DACVPM Clinical Study Design Tree No Comparison Basis? Explicit Control Group Historical Concurrent Randomized Factor Assignment? Observational Study "Direction"? Case Series Case Report Self-controlled Trial Case-Control Study Cross-Sectional Study (prevalence study) Ecological Study [Aggregate data] Cohort Study (incidence study) Randomized Blinded Controlled Trial (RBCT) Randomized Cross-Over Trial Experimentally induced Disease Unique: Diagnostic Test Evaluation [two parallel studies] Retrospective from Outcome Prospective from Exposure Timing of Control Group? Experimental Strength Strength Strength Yes None Strength Implicit Control Group
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Intro to Clinical Research JM Gay, DVM PhD DACVPM Study Weak Points and Their Correction Reduced by: Establishing prior eligibility criteria Selecting from similar populations Blinding of selector Using random selection from a population
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Unformatted text preview: Reduced by: • Using objective, prospective, primary data • Blocking over time and batch and randomizing allocation within batch • Blinding of observer doing exams, running tests, reading films • Increasing objectivity of measurements, validating reliability of subjective scales Reduced by: • Increasing study size (4 fold increase halves imprecision) • Reducing measuring imprecision • Replicating imprecise measurements • Blocking, stratifying, pairing, or pre-post design may improve • Reducing subject heterogeneity • Adjusting initial size for potential loss (~20%) Confounding Bias Reduced by: • Using random assignment. • Using a concurrent control group • Restriction or matching of subjects on known confounders • Analytic control of known confounders • Minimizing differential losses to followup Systematic Bias Random Imprecision Sampling / Selection Bias Study Design Study Size Measurement Bias...
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This note was uploaded on 01/27/2012 for the course VMS 576 taught by Professor Johngay during the Spring '12 term at Washington State University .

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ClinicalDesignTree - Reduced by: • Using objective,...

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