The reliability of a food frequency questionnaire for use among adolescents

Abstract

Objectives-This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts.Methods-Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves.Results-The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast-and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years.Conclusion-Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.

Validation and reproducibility of dietary assessment methods in adolescents: a systematic literature review

“…General overview An overview of the retrieved twenty original articles (1,(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) is shown in Table 1.…”

“…The majority (n 17) (1,(13)(14)(15)(16)(17)(18)(19)(20)(22)(23)(24)26,27,(29)(30)(31) of them were identified as studies assessing the validation and reproducibility of FFQ against reference dietary instruments (Table 2), while the remaining three studies considered questionnaires other than FFQ analysed for their validity and reproducibility against different reference methods (21,25,28) ( Table 3). …”

“…The outcome in some cases included the values of validity and reproducibility of the instrument to assess both food and nutrient intakes (16,17,25,(28)(29)(30) , while some studies considered only the food intake (18,(20)(21)27) and some others only the nutrient intake (1,(13)(14)(15)19,(22)(23)(24)26,31) .…”

Comparative analysis of two FFQ

“…However, it is a booklet that takes 45 min to complete and has to be manually coded before the manual data entry, increasing both the respondent burden and the resources required to analyse the FFQ. The CSIRO FFQ had been validated by ourselves and others (7)(8)(9)(10) .The objectives of the present study were to examine the utility of the shorter FFQ compared with the longer FFQ and to establish the agreement between the CSIRO FFQ and the CCV FFQ, as there are advantages of reduced respondent burden and fewer professional resources of using a machine-readable FFQ. …”

“…However, it is a booklet that takes 45 min to complete and has to be manually coded before the manual data entry, increasing both the respondent burden and the resources required to analyse the FFQ. The CSIRO FFQ had been validated by ourselves and others (7)(8)(9)(10) .…”