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Biostatistics Bios600.001
Second Semester 20092010
Homework #2: Probability Models and their Applications in Public Health
Reminder: Save your SAS output files for each problem so that you might refer back to them in the
future and could show your work (e.g. for an unexpected audit!).
Due Date
9:30 am
in class on
Feb 2,
2009
Problem 1. Vitamin A Supplementation to Prevent Children’s Mortality in Nepal
Section 1:
Probability, Binomial and Poisson Models
Learning Objectives:
Students who successfully master this section will be able to:
1)
use the concepts of probability to describe the effect of Vitamin A on mortality;
2)
define and apply the term “effect modification” or equivalently “interaction” in a
randomized
trial;
3)
use the binomial distribution and the Poisson approximation to the binomial to
calculate probabilities of certain events.
Scientific Background:
Xerophthalmia, due to vitamin A deficiency, was long known to be a leading cause of childhood
blindness in the developing world.
However, in the late 1970s, Dr. Alfred Sommer and his Indonesian
colleagues observed that children with mild, nonblinding xerophthalmia (those having night
blindness or Bitot’s spots, which are dry patches that form on the conjunctiva) were at a 4fold higher
risk of dying than children with normal eyes.
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This note was uploaded on 02/24/2010 for the course BIOS 600 taught by Professor Staff during the Spring '08 term at UNC.
 Spring '08
 Staff

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