A cardiologist has a device that measures prothrombin clotting times (protimes) of patients who are taking the blood thinning drug Coumadin. One of his patients asks him about the precision of this measuring instrmen. He responds by saying that it is calibrated against certified standards on a daily basis. The patient persists " I'm not asking about accuracy, but precision - repeatability of measurements," to which the cardiologist responds "I'm sure it's just fine." (cardiologists tent to be a bit patronizing if not imperious when dealing with patients, and don't wnat to be bothered by what they perceive to be irrelevant detail.)
a) What, exactly, is the patient asking about the test? Identify the approptiate population paramete nedded to answer the patent's question.
b) The patient insists that the cardiologist conduct tests of 8 independent blood samples, one drawn from each of his fingers, and that a 99% confidence interval be constructed fo the parameter of part a) the datat are as follows: 12.2, 13.4, 11.9, 13.4, 12.1, 14.0, 12.5, 13.8
Construct the aforementioned confidence interval.