Twenty-four hour dietary recalls by fourth-grade children were not influenced by observations of school meals.

Objective: To investigate whether school-meal observations influenced children's 24-hour dietary recalls.
Study Design and Setting: Over three school years, 555 randomly selected fourth-grade children were interviewed to obtain a 24-hour dietary recall; before being interviewed, 374 children were observed eating two school meals (breakfast, lunch), and 181 children were not observed. Within observation-status groups (observed, unobserved), children were randomized within sex to one of six combinations from two target periods (prior 24 hours, previous day) crossed with three interview times (morning, afternoon, evening).
Results: For each of the five variables (interview length, meals/snacks, meal components, items, kilocalories), naïve and adjusted equivalence tests rejected that observation-status groups were different, indicating that school-meal observations did not influence children's 24-hour dietary recalls. There was a target-period effect on length (P<0.0001) (longer for prior-24-hour recalls), a school year effect on length (P=0.0002) (longer for third year), and a target period-interview time interaction on items (P=0.0110) and kilocalories (P=0.0047) (both smaller for previous-day recalls in the afternoon than prior-24-hour recalls in the afternoon and previous-day recalls in the evening), indicating that variables were sufficiently sensitive and psychometrically reliable.
Conclusion: Conclusions about 24-hour dietary recalls by fourth-grade children observed eating school meals in validation studies are generalizable to 24-hour dietary recalls by comparable but unobserved children in nonvalidation studies.