Objective: To evaluate the validity, reliability and sensitivity of a computerised single day 24-h recall questionnaire designed for the comparison of children's fruit and snack consumption at the group (school) level.
Design: Relative validity and reliability were assessed in relation to (i) intake at school and (ii) intake throughout the whole day, using diary-assisted 24-h recall interviews and a 7-day test-retest procedure. Sensitivity was assessed in relation to intake by comparing results from schools with differing food policies, and by sex.
Subjects and setting: Eight schools took part in the validity and reliability assessments, with 78 children completing the 24-h recall interviews and 195 children completing the test-retest procedure. A total of 43 schools (1890 children) took part in the sensitivity analysis. All children were aged 9-11 y. All schools were in South Wales and South-west England.
Results: For fruit intake at school, the questionnaire showed fair levels of validity at the individual level (kappa = 0.29). At the group level, there were little or no differences in fruit intake at school between the two measures and two occasions. The questionnaire was sufficiently sensitive to identify statistically significant differences between girls and boys, and between schools with different food policies. For snack intake at school, validity at the individual level was slightly lower (kappa = 0.220.25), but the data remained of value in analyses at the group level. For fruit and snack intake throughout the whole day there was little agreement at the individual level (kappa = 0.00-0.06), and at the group level there tended to be substantial differences between the two measures and two occasions.
Conclusions: The computerised questionnaire is a quick and cost-effective means of assessing children's consumption of fruit at school. While further development is required to improve validity and reliability, it has the potential to be particularly useful in randomised controlled trials of school-based dietary interventions.