Table 3.
90th Percentile of the Absolute Mean Difference (AMD_90) for 12 Sites Selected from 90 via Four Methods
| Variable | Simple random sample |
MD with phantoms |
RMD_race++ with phantoms |
RMD_race++ with chameleons |
|---|---|---|---|---|
| NonWhite (%) | 23.1 | 3.9 | 1.7 | 2.0 |
| Female (%) | 2.1 | 0.9 | 0.9 | 1.1 |
| On Statins (%) | 5.4 | 0.4 | 0.8 | 0.7 |
| Systolic BP (mmHg) | 2.1 | 0.5 | 0.7 | 0.8 |
| BMI | 0.7 | 0.1 | 0.1 | 0.1 |
| A1c (%) | 0.2 | 0.1 | 0.1 | 0.1 |
| N patients | 177.0 | 28.8 | 17.3 | 17.0 |
12 sites selected via simple random samples for the simple randomization. 12 sites optimally selected using phantoms for MD and RMD_race++. 16 sites selected using chameleons with threshold equal to the 0.2 percentile of the distance matrix. Note a threshold equal to the 0.17 percentile yields the same 12 sites as using phantoms. RMD_race++ has weights=10 for race and BMI, 5 for statin use and N patients, and 1 otherwise. 500,000 simulations run for simple randomization and 10,000 for each of the other methods. Standard error for N patients ≤0.3, and ≤0.1 for all other variables.