TABLE 1.
Dietary assessment instrument combinations and approaches studied1
| Approaches | |||||
|---|---|---|---|---|---|
| Crude data | NCI-modeled data2 | ||||
| Dietary assessment | 1×R24W | 3×R24W | 1×R24WNCI | 3×R24WNCI | 3×R24W + wFFQNCI |
| Type of intake | Given day | Within-person mean | Usual | Usual | Usual |
| No. of R24W | 1 | 3 | 1 + second repeated in 40% | 3 | 3 |
| wFFQ | No | No | No | No | Yes |
1NCI, National Cancer Institute; R24W, web-based 24-h recall; wFFQ, web-based food-frequency questionnaire.
2The NCI method 2.1 was used to account for within-person variation and produce usual intake estimates. Covariates for the NCI method were recall sequence, weekend, and age. The FFQ data were considered only in the 3×R24W + wFFQNCI combination.