TABLE 1.
Descriptive Statistics for Daily PM2.5 and NO2
| PM2.5 (µg/m3) | NO2 (ppb) | |||
|---|---|---|---|---|
| All Daily Values (n = 1,334 Participants) | Unimputed Only (n = 1,324 Participants) | All Daily Values (n = 1,305 Participants) | Unimputed Only (n = 1,096 Participants) | |
| Nonmissing daily concentrations: N (%)a | 481,450 (99%) | 473,289 (99%) | 471,682 (100%) | 392,913 (99%) |
| Missing daily concentrations: n (% missing)b | 2,792 (1%) | 7,323 (2%) | 2,033 (0%) | 4,935 (1%) |
| Mean | 8.8 | 8.8 | 16.4 | 18.5 |
| Standard deviation (SD) | 7.6 | 7.6 | 13.7 | 13.7 |
| Median | 6.6 | 6.7 | 12.6 | 15.9 |
| Min | <0.001 | 0.05 | <0.001 | <0.001 |
| Max | 226.3 | 226.3 | 119.4 | 118.1 |
| Coefficient of variationc | 0.86 | 0.86 | 0.84 | 0.74 |
aN = number of MIREC participants × sum of all nonmissing gestational + pre-pregnancy days for each participant (i.e., for PM2.5, N = 1,334 participants × a maximum of 363 days per participant).
b% nonmissing = nonmissing values/maximum possible daily values × 100 (i.e., for PM2.5, the maximum % nonmissing = 481,450/484,242 × 100).
cCoefficient of variation (CV) = standard deviation/mean.