A physician and president of a Tampa Health Maintenance Organization (HMO) are attempting to show the benefits of managed health care to an insurance company. The physician believes that certain types of doctors are more cost-effective than others. One theory is that Primary Specialty is an important factor in measuring the cost-effectiveness of physicians. To investigate this, the president obtained independent random samples of 20 HMO physicians from each of 4 primary specialties - General Pract ice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) - and recorded the total charges per member per month for each. A second factor which the president believes influences total charges per member per month is whether the doctor is a foreign or USA medical school graduate. The president theorizes that foreign graduates will have higher mean charges than USA graduates. To investigate this, the president also collected data on 20 foreign medical school graduates in each of the 4 primary specialty types described above. So information on charges for 4 O doctors (20 foreign and 20 USA medical school graduates) was obtained for each of the 4 specialties. The results for the ANOVA are summarized in the following table. 3 Source Specialty Med school Interaction Error Total SS 22,855 105 890 18,950 42,800 MSF 7,618 105 297 60.94 0.84 2.38 PR>F 0.0001 0.6744 0.1348 152 159 Referring to the table above, what degrees of freedom should be used to determine the critical value of the Fratio against which to test for differences in the mean charges for doctors among the four primary specialty areas? numerator df = 3, denominator df = 159 O numerator df = 1, denominator df = 152 O numerator df = 1, denominator df = 159 numerator df = 3, denominator df = 152 A physician and president of a Tampa Health Maintenance Organization (HMO) are attempting to show the benefits of managed health care to an insurance company. The physician believes that certain types of doctors are more cost-effective than others. One theory is that Primary Specialty is an important factor in measuring the cost-effectiveness of physicians. To investigate this, the president obtained independent random samples of 20 HMO physicians from each of 4 primary specialties - General Pract ice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) - and recorded the total charges per member per month for each. A second factor which the president believes influences total charges per member per month is whether the doctor is a foreign or USA medical school graduate. The president theorizes that foreign graduates will have higher mean charges than USA graduates. To investigate this, the president also collected data on 20 foreign medical school graduates in each of the 4 primary specialty types described above. So information on charges for 4 O doctors (20 foreign and 20 USA medical school graduates) was obtained for each of the 4 specialties. The results for the ANOVA are summarized in the following table. 3 Source Specialty Med school Interaction Error Total SS 22,855 105 890 18,950 42,800 MSF 7,618 105 297 60.94 0.84 2.38 PR>F 0.0001 0.6744 0.1348 152 159 Referring to the table above, what degrees of freedom should be used to determine the critical value of the Fratio against which to test for differences in the mean charges for doctors among the four primary specialty areas? numerator df = 3, denominator df = 159 O numerator df = 1, denominator df = 152 O numerator df = 1, denominator df = 159 numerator df = 3, denominator df = 152