Question

Vitamin D is needed for the body to use calcium. An experiment is designed the effects of calcium and vitamin D supplements on the bones of first-year college students. The outcome measure is the total body mineral content (TBBMC), a measure of bone health. Three doses of calcium wil be used: 0, 200, and 400 mg/day. The doses of vitamin D will be 0, 50, and 100 international units (IU) per day. The calcium and vitamin D will be given in a single tablet. Al tablets including those with no calcium and no vitamin D will look identical. Subjects for the study will be 90 men and 90 women.a) What are the factors and the treatments for this experiment?b) Draw a picture explaining how you would randomize the 180 college students to the treatmentsc) Use a spreadsheet to carry out the randomization

Answer 1

(a) The factors are calcium dose, and Vitamin D dose. There are 9 treatments (each calcium/vitamin D combination).

(b) Assign 20 students to each group, with 10 of each gender. The complete diagram would have a total of 18 branches.

SUBJECTS:

Men---> Random Assignment---> Group 1---> Treatment 1---> measure TBBMC

Men---> Random Assignment---> Group 2---> Treatment 2---> measure TBBMC

Men---> Random Assignment---> Group 3---> Treatment 3---> measure TBBMC

Men---> Random Assignment---> Group 4---> Treatment 4---> measure TBBMC

Men---> Random Assignment---> Group 5---> Treatment 5---> measure TBBMC

Men---> Random Assignment---> Group 6---> Treatment 6---> measure TBBMC

Men---> Random Assignment---> Group 7---> Treatment 7---> measure TBBMC

Men---> Random Assignment---> Group 8---> Treatment 8---> measure TBBMC

Men---> Random Assignment---> Group 9---> Treatment 9---> measure TBBMC

Women---> Random Assignment---> Group 1---> Treatment 1---> measure TBBMC

Women---> Random Assignment---> Group 2---> Treatment 2---> measure TBBMC

Women---> Random Assignment---> Group 3---> Treatment 3---> measure TBBMC

Women---> Random Assignment---> Group 4---> Treatment 4---> measure TBBMC

Women---> Random Assignment---> Group 5---> Treatment 5---> measure TBBMC

Women---> Random Assignment---> Group 6---> Treatment 6---> measure TBBMC

Women---> Random Assignment---> Group 7---> Treatment 7---> measure TBBMC

Women---> Random Assignment---> Group 8---> Treatment 8---> measure TBBMC

Women---> Random Assignment---> Group 9---> Treatment 9---> measure TBBMC

(c) Randomization results will vary.