A Normal model states that if we draw repeated random samples of the same size, n, from some population and measure sample proportions, then the collection of these
Proportions will pile up around the underlying population proportion, p. The requirement
For this to work is
A) np and nq must be at least equal to 10.
B) As n increases, a distribution of sample proportions becomes more Normal.
C) np and nq must be less than 10.
D) Both B and C.
E) Both A and B.

Question

Quizplus · Accepted Answer

This is known as the normal approximation to the binomial distribution. The sample size, n, must be large enough so that np and nq (where q=1-p) are at least equal to 10. As n increases, the distribution of sample proportions becomes more Normal. Therefore, both options A and B are required for the Normal model to work.

A Normal Model States That If We Draw Repeated Random