Question

1.   In a study of 1228 randomly selected medical malpractice lawsuits, it is found that 856 of them were later dropped or dismissed (based on data from the Physician Insurers Association of America).  Use this data to construct a 99% confidence interval for the proportion of all medical malpractice lawsuits that are either dropped or dismissed.

Answer 1

Sample proportion = 856 / 1228 = 0.697

99% confidence interval for p is

- Z/2 * sqrt [ ( 1 - ) / n ] < p < + Z/2 * sqrt [ ( 1 - ) / n ]

0.697 - 2.5758 * sqrt [ 0.697 ( 1 - 0.697) / 1228] < p < 0.697 + 2.5758 * sqrt [ 0.697 ( 1 - 0.697) / 1228]

0.663 < p < 0.731

99% CI is ( 0.663 , 0.731 )