Table 2.
Sample mean and standard deviation for two biased measures of folate intake — dietary folate (FFQ) and 24-hour recall — from 172 women in the PIN substudy. Both FFQ and 24-hour recall measurements are reported on the log-scale with the 24-hour recall attempted three times per trimester and FFQ attempted once per trimester.
| Instrument | Trimester | Rep | N | Mean | SD |
|---|---|---|---|---|---|
| 1 | 1 | 97 | 5.92 | 0.46 | |
| FFQ | 2 | 1 | 134 | 6.00 | 0.35 |
| 3 | 1 | 72 | 6.00 | 0.42 | |
| 1 | 1 | 141 | 5.62 | 0.62 | |
| 1 | 2 | 104 | 5.61 | 0.68 | |
| 1 | 3 | 16 | 5.18 | 0.43 | |
| 2 | 1 | 125 | 5.72 | 0.55 | |
| 24-hour recall | 2 | 2 | 95 | 5.84 | 0.48 |
| 2 | 3 | 5 | 5.55 | 0.58 | |
| 3 | 1 | 116 | 5.87 | 0.56 | |
| 3 | 2 | 87 | 5.91 | 0.51 | |
| 3 | 3 | 2 | 6.14 | 0.22 |