Calcium and vitamin D. Vitamin D is needed for the body to use
calcium. An experiment is designed to study the effects of calcium
and vitamin D supplements on the bones of first-year college
students. The outcome measure is the total body bone mineral
content (TBBMC), a measure of bone health. Three doses of calcium
will be used: 0, 250, and 500 milligrams per day (mg/day). The
doses of vitamin D will be 0, 75, and 150 international units (IU)...