A Certain HMO Is Attempting to Show the Benefits of Managed

Multiple Choice

A certain HMO is attempting to show the benefits of managed health care to an insurance company. The HMO believes that certain types of doctors are more cost-effective than others. One theory is that both primary specialty and whether the physician is a foreign or USA medical school graduate are an important factors in measuring the cost-effectiveness of physicians. To investigate this, the president obtained independent random samples of $40 \mathrm { HMO }$ physicians, half foreign graduates and half USA graduates, from each of four primary specialties-General Practice (GP) , Internal Medicine (IM) , Pediatrics (PED) , and Family Physician (FP) - and recorded the total per-member, per-month charges for each. Thus, information on charges were obtained for a total of $n = 160$ doctors. The ANOVA results are summarized in the following table.
$\begin{array} { l r r r r r } \text { Source } & \text { df } & \text { SS } & \text { MS } & \text { F Value } & \text { Prob > F } \\\hline \text { Specialty } & 3 & 22855 & 7618 & 60.94 & .0001 \\\text { Medschool } & 1 & 105 & 105 & 0.84 & .6744 \\\text { Interaction } & 3 & 890 & 297 & 2.38 & .1348 \\\text { Error } & 152 & 18950 & 125 & & \\\hline \text { Total } & 159 & 42800 & & & \\\hline\end{array}$

Interpret the test for interaction shown in the ANOVA table. Use $\alpha = 0.025$ .

A) There is sufficient evidence at the $\alpha = 0.025$ level to say that primary specialty and medical school do not interact.
B) There is insufficient evidence at the $\alpha = 0.025$ level to say that primary specialty and medical school interact.
C) There is sufficient evidence at the $\alpha = 0.025$ level to say that primary specialty and medical school interact.
D) It is impossible to make conclusions about primary specialty and medical school interaction based on the given information.