Table 2.
Power calculations to detect significant changes in weight for studies involving different bacterial inocula administered by bronchoscopic or surgical procedures.
| Power | Comparing CFU doses | Bronchoscope | Surgery | |||
|---|---|---|---|---|---|---|
| Needed sample size for analysis | Needed sample size for analysis | Mortality-corrected sample size | ||||
| Inoculum 1 | Inoculum 2 | Inoculum 1 | Inoculum 2 | |||
| 70% | 25,000 | 50,000 | 15 | 15 | 17 | 19 |
| 50,000 | 100,000 | 16 | 33 | 41 | 50 | |
| 25,000 | 100,000 | 7 | 5 | 6 | 8 | |
| 80% | 25,000 | 50,000 | 19 | 19 | 22 | 24 |
| 50,000 | 100,000 | 20 | 42 | 51 | 63 | |
| 25,000 | 100,000 | 9 | 7 | 8 | 11 | |
| 90% | 25,000 | 50,000 | 25 | 24 | 27 | 30 |
| 50,000 | 100,000 | 27 | 56 | 68 | 84 | |
| 25,000 | 100,000 | 11 | 8 | 9 | 12 | |
Three different levels of power (70%, 80%, and 90%) were estimated. The difference in mean weight change for each procedure was used together with standard deviation (Supplemental Table S1) to calculate the number of mice needed to perform the analysis of the studies at a significance level of 0.05. Because of bacterial dose-dependent mortality observed for mice undergoing the surgical procedure, the number of mice needed has been mortality corrected. Hence, the number of mice needed for inoculation on day 0 is higher than the number needed for the analysis.