Random assignment of volunteers to the treatment

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Unformatted text preview: mark of the College Entrance Examination Board. AP® Statistics 2000 ─ Scoring Guidelines Question 5 Solution (a) Describes an experimental design that includes: 1. Random assignment of volunteers to the treatment groups 2. Identification of treatment groups as old drug and new drug 3. Indication that a comparison or measurement of cholesterol levels should be made OR The student may give a detailed diagram that addresses the three parts: Group 1 Treatment 1 2. (old drug) Group 2 1. Random assignment of subjects Treatment 2 2. (new drug) 3. Compare Cholesterol Levels Note: In part (a), it is incorrect to use the terminology “treatment” and “placebo” for the treatment groups. It is considered correct to use “old drug” and “new drug”, and “placebo,” if a third group is used, for the treatment groups. (b) Describes an experimental design that includes: 1. Creating blocks based on level of exercise or cholesterol level, or creating blocks using age, diet, gender, or any other factor plausibly related to cholesterol level with explanation (i.e., block on gender because males and females may respond differently) 2. Random assignment of subjects to treatments within blocks OR The student may give a detailed diagram that addresses the two parts as long as the blocking factor is described. Block 1 (Exercise) Random Assignment of Subjects in Block 1 Block 2 (No exercise) Random Assignment of Subjects in Block 2 Volunteers Treatment 1 (old drug) Treatment 2 (new drug) Treatment 1 (old drug) Treatment 2 (new drug) Compare Cholesterol Levels Compare Cholesterol Levels Note: No credit will be given in part (b) if a student does not use blocking in his/her design even though they randomize correctly. Note: Crossover designs or matched-pairs designs that incorporate the idea of blocking are acceptable. Copyright © 2000 College Entrance Examination Board and Educational Testing Service. All rights reserved. AP is a registered trademark of the College Entrance Examination Board. AP® Statistics 2000...
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