WBR0365: Difference between revisions
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{{WBRQuestion | {{WBRQuestion | ||
|QuestionAuthor=[[User:Gonzalo Romero|Gonzalo A. Romero, M.D.]] [mailto:gromero@wikidoc.org] | |QuestionAuthor=[[User:Gonzalo Romero|Gonzalo A. Romero, M.D.]] [mailto:gromero@wikidoc.org] (Reviewed by Serge Korjian) | ||
|ExamType=USMLE Step 1 | |ExamType=USMLE Step 1 | ||
|MainCategory=Biostatistics/ Epidemiology | |MainCategory=Biostatistics/ Epidemiology | ||
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|MainCategory=Biostatistics/ Epidemiology | |MainCategory=Biostatistics/ Epidemiology | ||
|SubCategory=General Principles | |SubCategory=General Principles | ||
|Prompt=A research group is trying to study the effects of a short course of concentrated coffee bean extract on weight loss in healthy volunteers. They design a randomized double-blinded controlled trial and recruit 154 subjects. Subjects are randomized in into 2 groups one receiving 3 daily doses of coffee bean extract and the other receiving 3 daily doses of a placebo. At the end of the 6 month period, the biostatistician wants to | |Prompt=A research group is trying to study the effects of a short course of concentrated coffee bean extract on weight loss in healthy volunteers. They design a randomized double-blinded controlled trial and recruit 154 subjects. Subjects are randomized in into 2 groups one receiving 3 daily doses of coffee bean extract and the other receiving 3 daily doses of a placebo. At the end of the 6 month period, the biostatistician wants to compare the mean change in body weight from baseline in the 2 groups. Which of the following tests should the biostatistician use in order to obtain a valid comparison? | ||
|AnswerA=Chi-square | |AnswerA=Chi-square | ||
|AnswerAExp=[[Chi-square test|Chi-square]] is a test which allows to determine a difference between 2 or more proportions or percentages of categorical outcomes. | |AnswerAExp=[[Chi-square test|Chi-square]] is a test which allows to determine a difference between 2 or more proportions or percentages of categorical outcomes. |
Revision as of 15:24, 1 August 2014
Author | [[PageAuthor::Gonzalo A. Romero, M.D. [1] (Reviewed by Serge Korjian)]] |
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Exam Type | ExamType::USMLE Step 1 |
Main Category | MainCategory::Biostatistics/ Epidemiology |
Sub Category | SubCategory::General Principles |
Prompt | [[Prompt::A research group is trying to study the effects of a short course of concentrated coffee bean extract on weight loss in healthy volunteers. They design a randomized double-blinded controlled trial and recruit 154 subjects. Subjects are randomized in into 2 groups one receiving 3 daily doses of coffee bean extract and the other receiving 3 daily doses of a placebo. At the end of the 6 month period, the biostatistician wants to compare the mean change in body weight from baseline in the 2 groups. Which of the following tests should the biostatistician use in order to obtain a valid comparison?]] |
Answer A | AnswerA::Chi-square |
Answer A Explanation | [[AnswerAExp::Chi-square is a test which allows to determine a difference between 2 or more proportions or percentages of categorical outcomes.]] |
Answer B | AnswerB::ANOVA |
Answer B Explanation | [[AnswerBExp::ANOVA or analysis of variance allows to determine if a difference exists between the means of 3 or more groups. ANOVA (Analysis of Variance of 3 or more groups).]] |
Answer C | AnswerC::T-test |
Answer C Explanation | [[AnswerCExp::T-test allows to check for difference between the means of 2 groups.]] |
Answer D | AnswerD::Pearson correlation |
Answer D Explanation | [[AnswerDExp::Pearson correlation is a coefficient which allows to determine relationship, not to determine if statistical significance is achieved. It does not allow to determine causality. The relationship could be represented graphically; the more solid the line represented, the stronger the correlation. This correlation could vary from +1 to -1; varying from a directional relationship or inverse relationship respectively. The closer the absolute value to 1, the stronger the correlation being graphically represented as a line.]] |
Answer E | AnswerE::Power measure |
Answer E Explanation | AnswerEExp::Power measure |
Right Answer | RightAnswer::C |
Explanation | [[Explanation:: Educational Objective: T- test is used to check if a difference exists between the means of 2 groups. |
Approved | Approved::Yes |
Keyword | |
Linked Question | Linked:: |
Order in Linked Questions | LinkedOrder:: |