A Certain HMO Is Attempting to Show the Benefits of Managed

A certain HMO is attempting to show the benefits of managed care to an insurance company. The HMO believes that certain types of doctors are more cost-effective than others. One theory is that certification level is an important factor in measuring the cost-effectiveness of physicians. To investigate this, the HMO obtained independent random samples of 26 physicians from each of the three certification levels-Board certified (C) ; Uncertified, board eligible (E) ; and Uncertified, board ineligible (I) - and recorded the total per member per month charges for each (a total of 78 Physicians) . How many factors are present in this study?

A) 26
B) 1
C) 3
D) 78