TABLE 2.

Key characteristics of dietary instruments to measure in-school diet quality among children (n = 22 studies)¹

Dietary instrument	Strengths	Limitations	Evidence of relative accuracy2	Evidence of reliability3
Self-report methods
School meal recalls	Opportunity to probe for detailed dietary information and portion sizes, low burden on subjects	Costly if interviewer-administered, relies on memory, subject to misreporting, prone to social desirability bias	Poor accuracy for individual foods reported (n = 8 of 12 studies); acceptable accuracy when reporting amounts consumed (n = 4 of 5 studies), acceptable energy report rates (n = 2 of 3 studies)	N/A
Estimated food records (by study subjects)	Detailed dietary information (quantities and types of food), self-administered, does not rely on memory	Higher burden on subjects, subject to misreporting, prone to reactivity and social desirability bias	Acceptable accuracy with daily monitoring but poor when children are monitored on a weekly basis (n = 1 study)	N/A
FFQs	Can provide estimates of usual intakes, self-administered (so lower costs)	Finite food list, lower precision for amounts consumed, difficult to capture contextual information (e.g., time and place of consumption), cognitively challenging for younger age groups, subject to misreporting, prone to social desirability bias	Acceptable accuracy for measuring select beverages and snack foods (n = 1 study)	N/A
Observational methods
In-person meal observations	Precise information about amounts and types of foods; lowest burden on subjects, more objective method	Costly, labor-intensive, potentially intrusive	Acceptable accuracy (n = 1 study)	Good interrater reliability (n = 11 studies)
Weighed food records (by research staff)	Precise information about amounts and types of foods; lowest burden on subjects, more objective method	Most costly method, labor-intensive, not well suited for environments where students bring home-packed lunches	No evidence4	No evidence
Digital photography methods	Low burden on participants; quick to administer, can be self-administered (so lower cost), more objective method	Costly (labor-intensive for dietary data entry), difficult to capture hidden or wasted or spilled or traded foods, can be challenging to interpret data from photos	Acceptable accuracy (n = 2 studies)	Acceptable interrater reliability (n = 2 studies)
School food checklist	Only validated to measure energy intake for a group; quick to administer (∼3 min/child), more objective method	Finite food list, labor-intensive, potentially intrusive, not validated to assess the quality of intake (only energy)	Acceptable accuracy (n = 1 study)	Acceptable interrater reliability (n = 1 of 2 studies); good intrarater reliability (n = 1 study)

¹N/A, not applicable.

²A measure of accuracy was expressed by using categorical ratings (poor or failing compared with acceptable) defined with cutoffs shown in Table 1.

³Interrater and intrarater reliability is applicable to observational tools only.

⁴There is no gold standard in dietary assessment methodology, but weighed food records by trained raters and observers are regarded as the closest to a gold standard. We found no methodological study testing the relative accuracy of the weighed food record. The plate-waste method (a form of weighed food record in which weights of foods remaining on the plate at the end of the meal are subtracted from the amounts served) is an adaptation of the weighed food record.