Summary Tables: Recommendations on Potential Approaches to Dietary Assessment for Different Research Objectives Requiring Group-level Estimates
List of tables
- Approach
- Describing dietary intake
- Examining association between diet as an independent variable and a dependent variable (e.g., health status)
- Examining association between an independent variable (e.g., self efficacy or socioeconomic status) and diet as a dependent variable
- Examining the effect of an intervention
These summary tables provide an overview of potential approaches to dietary assessment and indicate which approaches we recommend for different research objectives, given the current evidence. The research objectives considered are limited to those that require group-level estimates of dietary intake, not those that require estimates of intake for a given individual (Learn More about Deriving Group-level Estimates from Individual-level Intakes). Further, our focus is mainly on objectives related to estimating [glossary term:] usual dietary intakes, though we do also consider estimating acute intake when relevant.
The top row of the table indicates a continuum across the approaches in terms of the type and amount of information provided, analytic flexibility, investigator and respondent burden, and cost. However, the recommendations themselves are driven by the quality and appropriateness of the approach for the specific research objective. In other words, the recommended approaches may reflect ideal circumstances in which practical considerations, such as cost, respondent burden and administration time, do not impose constraints.
Details of Recommendations and Further Considerations, which accompanies these tables, provides more details on our recommendations and discusses further considerations about data capture and data analysis issues involved in studies that address the major types of research objectives.
For more information on the types of instruments featured in the tables and discussed in Details of Recommendations and Further Considerations, see the Instrument Profiles. For an at-a-glance comparison of the major features of these dietary assessment instruments, see the Compare Dietary Assessment Instruments table.
For more information about determining the [glossary term:] accuracy of self-report instruments and issues in [glossary term:] measurement error - two critical issues in conducting dietary assessment research - see Key Concepts.
Recommendations on potential approaches to dietary assessment for different research objectives requiring group-level estimates a,b,c
More:
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Less:
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| x(24HR) + FFQ Multiple administration of 24HR plus FFQ on whole sample |
x(24HR) Multiple administration of 24HR on whole sample |
24HR + x(24HR) Single administration of 24HR on whole sample plus repeat(s) on subsample |
FFQ/SCR + x(24HR) FFQ/SCR on whole sample plus multiple administrations of 24HR on subsample |
24HR Single administration of 24HR on whole sample |
FFQ FFQ on whole sample |
SCR Screener on whole sample |
|---|---|---|---|---|---|---|
| 1. Mean (µ) usual intake | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Acceptable, if calibrated to 24HRe | Recommended | Possiblei | Possiblei |
| 2. Difference between two groups in mean usual intake (µA - µB) | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Acceptable, if calibrated to 24HRe | Recommended | Possiblei | Possiblei |
| 3. Mean (µ), proportion of individuals (p) above/below some threshold, and percentiles (qp) of usual intake (usual intake distribution) | ||||||
| More than necessaryd | Recommended | Acceptable, if subsample large enough | Acceptable, if calibrated to 24HRe | Possibleh | Not recommendedf | Not recommendedg |
| 4. Mean (µ), proportion of individuals (p) above/below some threshold, and percentiles (qp) of intake on a given day (acute intake distribution) | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Not recommended | Recommended | Not recommended | Not recommended |
| x(24HR) + FFQ Multiple administration of 24HR plus FFQ on whole sample |
x(24HR) Multiple administration of 24HR on whole sample |
24HR + x(24HR) Single administration of 24HR on whole sample plus repeat(s) on subsample |
FFQ/SCR + x(24HR) FFQ/SCR on whole sample plus multiple administrations of 24HR on subsample |
24HR Single administration of 24HR on whole sample |
FFQ FFQ on whole sample |
SCR Screener on whole sample |
|---|---|---|---|---|---|---|
| 5. Regression coefficients (β) for prospective or cross-sectional studies | ||||||
| Ideal | Recommended | Recommended | Acceptable, if calibrated to 24HR, using regression calibratione | Not recommended j | Possiblei | Possiblei |
| 6. Regression coefficients (β) for retrospective studies | ||||||
| Not possible | Not possible | Not possible | Not possible | Not possible | Possiblef | Possibleg |
| x(24HR) + FFQ Multiple administration of 24HR plus FFQ on whole sample |
x(24HR) Multiple administration of 24HR on whole sample |
24HR + x(24HR) Single administration of 24HR on whole sample plus repeat(s) on subsample |
FFQ/SCR + x(24HR) FFQ/SCR on whole sample plus multiple administrations of 24HR on subsample |
24HR Single administration of 24HR on whole sample |
FFQ FFQ on whole sample |
SCR Screener on whole sample |
|---|---|---|---|---|---|---|
| 7. Regression coefficients (β) for prospective or cross-sectional studies | ||||||
| More than necessary | Recommended | Acceptable | Acceptable, if calibrated to 24HR, using regression calibration | Acceptable | Possiblei | Possiblei |
| 8. Regression coefficients (β) for retrospective studies | ||||||
| Not possible | Not possible | Not possible | Not possible | Not possible | Possiblef | Possibleg |
| x(24HR) + FFQ Multiple administration of 24HR plus FFQ on whole sample at each point in time |
x(24HR) Multiple administration of 24HR on whole sample at each point in time |
24HR + x(24HR) Single administration of 24HR on whole sample plus repeat(s) on subsample at each point in time |
FFQ/SCR + x(24HR) FFQ/SCR on whole sample plus multiple administrations of 24HR on subsample at each point in time |
24HR Single administration of 24HR on whole sample at each point in time |
FFQ FFQ on whole sample at each point in time |
SCR Screener on whole sample at each point in time |
|---|---|---|---|---|---|---|
| 9. Determining change, between two points in time, in mean usual intake of group (µpost - µpre) | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Acceptable, if calibrated to 24HRe | Recommended | Possiblei | Possiblei |
| 10. Determining difference between two groups in mean usual intake change (µ(post - pre)i)A - (µ(post - pre)i)B | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Acceptable, if calibrated to 24HRe | Recommended | Possiblei | Possiblei |
| 11. Determining difference between two groups in post-intervention mean usual intake (µA, post - µB, post) | ||||||
| More than necessaryd | More than necessaryd | More than necessaryd | Acceptable, if calibrated to 24HRe | Recommended | Possiblei | Possiblei |
| 12. Determining change, between two points in time, in proportion of individuals above/below some threshold (p post - ppre) | ||||||
| More than necessaryd | Recommended | Acceptable, if subsample large enough | Acceptable, if calibrated to 24HRe | Possibleh | Possiblei | Possiblei |
| 13. Determining difference between two groups in change in proportion of individuals above/below some threshold (pA, post - pA, pre) - (pB, post - pB, pre) |
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| More than necessaryd | Recommended | Acceptable, if subsample large enough | Acceptable, if calibrated to 24HRe | Possibleh | Possiblei | Possiblei |
| 14. Determining difference between two groups in post-intervention in proportion of individuals above/below some threshold (pA, post - pB, post) | ||||||
| More than necessaryd | Recommended | Acceptable, if subsample large enough | Acceptable, if calibrated to 24HRe | Possibleh | Possiblei | Possiblei |
24HR: 24-hour recall
FFQ: food frequency questionnaire
SCR: screener
a This table refers to the assessment of any food or nutrient consumed as part of diet (not including supplements).
b For approaches involving more than one instrument, the first instrument listed is considered the main instrument (Learn More about Combining Instruments).
c Throughout the table, whenever 24-hour recalls are mentioned, food records could be employed in the same fashion because they also capture short-term intake with more detail than a frequency instrument. However, there is much less evidence available on the measurement error properties of food records, and the act of recording is known to cause reactivity.
d Approach will work, but provides more data than necessary to provide estimate for this objective.
e Energy-adjustment is recommended but is not possible with screeners.
f Approach is possible, but not recommended because absolute values are likely to be [glossary term:] biased. Energy-adjusted values may be less biased.
g Approach is possible, but not recommended because absolute values are likely to be biased, and energy adjustment is not possible with screeners.
h Estimated distributions will be too wide unless an estimate of the ratio of within-person to the sum of the within- plus between-person variation from an external study with a comparable sample is available.
i Estimates are likely to be biased but this bias can be corrected to some degree if frequency instrument is calibrated to less-biased instrument through an external calibration study.
j Approach is possible, but measurement error correction is not possible.
k Intervention associated recall bias, if present, contradicts the assumption that there is no [glossary term:] differential bias between control and intervention groups. In addition, [glossary term:] reactivity bias in food records may be particularly problematic for evaluating the effect of interventions.