PROBLEM 5E

(In some of the exercises that follow, we must make assumptions such as the existence of normal distributions with equal variances.)

Some nurses in county public health conducted a survey of women who had received inadequate prenatal care. They used information from birth certificates to select mothers for the survey. The mothers selected were divided into two groups: 14 mothers who said they had five or fewer prenatal visits and 14 mothers who said they had six or more prenatal visits. Let X and Y equal the respective birth weights of the babies from these two sets of mothers, and assume that the distribution of X is N(μX, σ2) and the distribution of Y is N(μY, σ2).

(a) Define the test statistic and critical region for testing H0: μX − μY = 0 against H1: μX − μY < 0. Let α = 0.05.

(b) Given that the observations of X were

and the observations of Y were

calculate the value of the test statistic and state your conclusion.

(c) Approximate the p-value.

(d) Construct box plots on the same figure for these two sets of data. Do the box plots support your conclusion?

Chapter 3 Notes – The fetus and newborn: health and risk I. Prenatal health and risk a. Infertility – inability to conceive successfully – after trying for a year i. One in 6 couples experience it ii. In vitro fertilization – assisted reproductive technology – one of the mother’s ova is surgically removed and joined with the fathers sperm 1. Once the ova and sperm fertilized and become an embryo – it is surgically placed back in the mother 2. Very expensive iii. Embryo cryopreservation – many ova being removed from the mother and frozen iv. Sper