Question

11.9 The Bureau of Labor Statistics report referenced in the previous exercise also reported that 7.3% of high school graduates were unemployed in October 2013 and 5.7% of high school graduates were unemployed in October 2014. Suppose that the reported percentages were based on inde- pendently selected representative samples of 400 high school graduates in each of these 2 years. a. Construct and interpret a 99% large-sample confi- dence interval for the difference in the proportions of high school graduates who were unemployed in these 2 years. than the confidence interval calculated in the previous exercise? Give two reasons why it is wider or narrower.

Answer 1

a)

October 2013 October 2014 29 23 0.0730 0.0570 400 400 estimated difference in proportion 0.0160 p,-Pz std error Se 0.0174 for 99 % Cl value of z= 2.576 margin of error E-z*std error 0.0449 lower confidence bound- 0.0289 lower confidence bound- 0.0609

from above 99% confidence interval for 99% large sample confidence interval for the difference in the proportions of high school graduates =-0.029 ; 0.061

b)

previous excercise is needed to answer the part (b)