Question

Problem 3) In 2015 a national vital statistics report indicated that 3.4 percent of all births produced twins. [Be sure you use at least two nonzero decimals in this problem. For example, use 0.034, not 0.03] An epidemiologist wants to know if the twin birth rate for very young mothers differs from the national value. She collects a random sample of 469 teenage girls who recently gave birth, and finds that 15 of them had twins.

a) Consider just one experimental unit – that is, one birth to a young teenager. What is the response variable? Categorical or quantitative?

b) The epidemiologist wants to conduct a significance test to decide if there is sufficient evidence that the twin birth rate for very young mothers differs from the national value. Verify the conditions for using the normal approximation for the sample proportion.

c) Conduct the significance test. Keep two nonzero digits in your calculation for ?̂ and for the standard deviation. Sketch the distribution for ?̂ showing mean and area for P-value. State your conclusion in plain English in the context of the problem. Look at the statements for Problem 1 and use them as a guide.

Answer 1