WBR0365
| Author | [[PageAuthor::Gonzalo A. Romero, M.D. [1]]] |
|---|---|
| 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 compares 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:: |