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Biostatistics and experimental design

Biostatistics and experimental design - Experimental...

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    Experimental Studies
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    Epidemiological vs  Experimental Studies Epidemiological studies are either  observational or experimental.  Observational studies are considered  “natural” experiments while  experimental studies are considered  true experiments
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    Experimental Studies Investigator assigns exposure to study  subjects Experimental studies most closely resemble  controlled laboratory experiments and serve  as models for the conduct of observational  studies. They are the gold standard of epidemiological  research. They have high status and validity,  and can pick up small and modest effects
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    Design of Experimental  Studies Study subjects recruited based on specific  criteria and their informed consent is sought Eligible and willing subjects randomly  allocated to receive one of the two or more  interventions being compared Study groups are monitored for outcome  under study (recurrence of disease, first  occurrence of disease, getting better, side  effects) Rates of the outcome in the various groups  are compared
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    Experimental Design Placebos are used to make the groups as comparable as  possible Subjects do not know if they are receiving treatment or placebo  (single blind); neither subjects nor investigators know who is  receiving treatment or placebo (double blind) Study requires active participation and cooperation of  participants (but deviations from the protocol will occur related  to side effects, illness, level of interest, and length of follow-up) Strategies to enhance compliance exist at the design phase (pick  an interested group and design a simple protocol) and during the  study itself (frequent contact with subjects, incentives to continue,  such as free check-ups) Noncompliance reduces the ability of the investigator to detect a  difference between the groups
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    Ethical Considerations Must be genuine doubt about efficacy of  treatment yet sufficient belief that it may  work What if it becomes apparent, before the  trial is over, that the new treatment is  beneficial (and should not be withheld  from the placebo group) or is toxic (and  treatment should be withdrawn)?
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    Interpretation of Results Is there a statistically significant  difference between the treated and  control groups? The study may not be powerful enough to  detect a difference between the groups  due to an insufficient number of  participants
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    Biostatistics
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    What is Biostatistics?
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