Chapter1.4+Chapter2

Chapter1.4+Chapter2 - 1.4 Experimental Design A researcher...

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1.4 Experimental Design A researcher wants to prove a new drug is effective  for common cold:  He invites a man with a heavy cold to try the new  medicine Two days later the man is cured  Can we say that this drug is effective?
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Definitions 1.5 Treatment : Each experimental condition is called a  treatment. Subject : Individuals or items on which the  experiment is performed. Control : Two or more treatments should be  compared Treatment Group : The group receiving specified  treatment Control Group : The group receiving placebo
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Definition 1.6 Randomization : Experimental units are randomly  divided into groups to avoid unintentional selection  bias
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Definition 1.7 Replication : have more than one observation under  the same treatment
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Advantage of Randomization : Potential confounding  variables can be equally balanced in the two groups so  whatever effects they might have will cancel out.  Advantage of Replication : improve the significance of  experimental results and reduce variability. More sample  size- more powerful          Principle of Experimental Design Control  Randomization Replication
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Terminology of Experimental Design Factor  (Independent variable): explanatory variable  manipulated by the experimenter Level : possible values of a factor Response Variable  (Dependent variable)  experimental outcome to be measured Treatment : combination of factor levels
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Identify treatment and response variable  for the following experiment: To study possible effects of Vitamin C and Vitamin E  on health Two factors:  dosage of Vitamin C and dosage of  Vitamin E Vitamin C has 3 levels: 0mg per day, 250 mg per  day, 500 mg per day Vitamin E has 2 levels: 0mg per day  400 mg per day
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Definition 1.7
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Chapter1.4+Chapter2 - 1.4 Experimental Design A researcher...

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