Table 1. Power of Statistical Tests of Physician Organization Efficiency, by Number of Assigned Patients and Efficiency, in the Boston Metropolitan Statistical Area: 2002.
| Percent Difference of Physician Organization from Average Efficiency (Better or Worse) | Number of Assigned Patients | ||||||
|---|---|---|---|---|---|---|---|
|
| |||||||
| 100 | 500 | 1,000 | 2,000 | 5,000 | 10,000 | 20,000 | |
|
| |||||||
| Percent | |||||||
| 5 | 1 | 2 | 4 | 7 | 19 | 43 | 80 |
| 10 | 2 | 7 | 15 | 33 | 80 | 99 | 100 |
| 15 | 3 | 17 | 38 | 74 | 99 | 100 | 100 |
| 20 | 5 | 33 | 68 | 96 | 100 | 100 | 100 |
| 25 | 8 | 54 | 89 | 100 | 100 | 100 | 100 |
| 30 | 12 | 74 | 98 | 100 | 100 | 100 | 100 |
| 50 | 43 | 100 | 100 | 100 | 100 | 100 | 100 |
NOTES: Two-sided test of the difference of the observed/expected expenditure ratio from 1. Significance level of the test is 1 percent. Standard deviation of the population is 2.08 (measured in Boston 2002 Medicare data and adjusted for case mix, geographic location, and hospital add-on payments). Power is the probability of rejecting the null hypothesis of average efficiency when it is false.
SOURCE: Pope, G.C. and Kautter, J., RTI International, Waltham, MA.