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 that were selected were divided into two groups: 14 mothers who said they had 5 or fewer prenatal visits and 14 mothers who said they had 6 or more prenatal visits. Let X and Y equal the respective birthweights of the babies from these two sets of mothers and assume that the distribution of X is N(\mu x, \sigma ^{2}) and the distribution of Y is N(\mu y, \sigma ^{2}).
a.) Define the test statistic and critical region for testing H0:\mu x -\mu y = 0against H1:\mu x -\mu y < 0. Let\alpha= 0.05.
b.) Given that the observations of X were: 49, 108, 110, 82, 93, 114, 134, 114, 96, 52, 101, 114, 120, 116 and the observations of Y were: 133, 108, 93, 119, 119, 98, 106, 131, 87, 153, 116, 129, 97, 110 calculate the value of the test statistic and state your conclustion.
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?
e.) Test whether the assumption of equal variances is valid. Let\alpha= 0.05.