Table 4.
Attenuation Factors for and Correlations Between Daily Dietary Intake Derived From the Oxford WebQ Tool and Estimated True Longer-Term Intake for Repeat Administrations of the Oxford WebQ, London, United Kingdom, 2014–2016a,b
| Nutrient Measure and No. of Repeat Administrations | Attenuation Factor | 95% CI | Correlation With True Intake | 95% CI |
|---|---|---|---|---|
| Nutrient intake, g | ||||
| Protein | ||||
| 1 | 0.27 | 0.17, 0.36 | 0.40 | 0.27, 0.52 |
| 2 | 0.37 | 0.24, 0.49 | 0.47 | 0.33, 0.61 |
| 3 | 0.42 | 0.28, 0.56 | 0.50 | 0.35, 0.65 |
| 4 | 0.45 | 0.30, 0.60 | 0.52 | 0.37, 0.67 |
| 5 | 0.48 | 0.32, 0.64 | 0.53 | 0.38, 0.69 |
| Potassium | ||||
| 1 | 0.31 | 0.18, 0.44 | 0.34 | 0.20, 0.47 |
| 2 | 0.42 | 0.25, 0.60 | 0.39 | 0.24, 0.54 |
| 3 | 0.48 | 0.28, 0.68 | 0.42 | 0.26, 0.58 |
| 4 | 0.52 | 0.30, 0.73 | 0.44 | 0.27, 0.60 |
| 5 | 0.54 | 0.32, 0.77 | 0.45 | 0.28, 0.62 |
| Total sugars | ||||
| 1 | 0.31 | 0.18, 0.44 | 0.33 | 0.20, 0.46 |
| 2 | 0.45 | 0.26, 0.64 | 0.40 | 0.24, 0.55 |
| 3 | 0.53 | 0.31, 0.75 | 0.43 | 0.27, 0.60 |
| 4 | 0.59 | 0.34, 0.83 | 0.45 | 0.28, 0.62 |
| 5 | 0.62 | 0.36, 0.88 | 0.47 | 0.29, 0.64 |
| Total energy expenditure, MJ | ||||
| 1 | 0.22 | 0.12, 0.33 | 0.32 | 0.18, 0.46 |
| 2 | 0.31 | 0.16, 0.45 | 0.38 | 0.21, 0.54 |
| 3 | 0.35 | 0.19, 0.52 | 0.40 | 0.23, 0.58 |
| 4 | 0.38 | 0.20, 0.56 | 0.42 | 0.24, 0.60 |
| 5 | 0.40 | 0.21, 0.59 | 0.43 | 0.24, 0.62 |
| Nutrient densityc, g/MJ | ||||
| Protein | ||||
| 1 | 0.34 | 0.17, 0.51 | 0.29 | 0.16, 0.42 |
| 2 | 0.51 | 0.27, 0.76 | 0.36 | 0.20, 0.51 |
| 3 | 0.62 | 0.32, 0.91 | 0.39 | 0.22, 0.56 |
| 4 | 0.69 | 0.36, 1.01 | 0.41 | 0.23, 0.59 |
| 5 | 0.73 | 0.38, 1.09 | 0.42 | 0.24, 0.61 |
| Potassium | ||||
| 1 | 0.33 | 0.12, 0.54 | 0.23 | 0.09, 0.37 |
| 2 | 0.48 | 0.17, 0.78 | 0.28 | 0.11, 0.44 |
| 3 | 0.57 | 0.21, 0.93 | 0.30 | 0.12, 0.48 |
| 4 | 0.62 | 0.23, 1.02 | 0.31 | 0.12, 0.50 |
| 5 | 0.66 | 0.24, 1.09 | 0.32 | 0.13, 0.52 |
| Total sugars | ||||
| 1 | 0.32 | 0.15, 0.50 | 0.27 | 0.13, 0.41 |
| 2 | 0.49 | 0.23, 0.75 | 0.33 | 0.16, 0.50 |
| 3 | 0.59 | 0.28, 0.91 | 0.36 | 0.18, 0.55 |
| 4 | 0.66 | 0.31, 1.01 | 0.38 | 0.19, 0.58 |
| 5 | 0.71 | 0.33, 1.09 | 0.40 | 0.20, 0.60 |
Abbreviation: CI, confidence interval.
a Data for all dietary measures and estimates were log-transformed.
b Estimates of measurement properties for the mean of repeated administrations of the tool are based on the parameters provided in Web Table 1, using the approach described by Schatzkin et al. (40).
c Nutrient density for protein, potassium, and total sugars was expressed in grams per MJ of total energy intake.