Waist-to-Height Ratio: NHANES Microdata Derivation
FitnessNorms derived WHtR from the CDC public body-measures and demographics files because NCHS does not publish this sex-by-age percentile table. The displayed values are transparent internal calculations, not official CDC estimates.
- Cohort: adults aged 20 and older with positive
BMXWAIST,BMXHT, andWTMEC2YR; known pregnancies inRIDEXPRGare excluded. Final n=5,718; the smallest sex-by-age cell contains 136 people. - Calculation: WHtR equals
BMXWAISTdivided byBMXHT. Both inputs are centimetres. - Quantiles: P5, P25, P50, P75, and P95 use linear interpolation on midpoint cumulative-weight positions within each sex and 5-year age group.
- Survey design: MEC weights are applied to point estimates. Strata, clusters, and survey-design standard errors are not calculated.
Why the earlier pool was retired
The former page pooled 2015-2016, 2017-March 2020, and 2021-2023 and checked only medians. Review found that dividing every release weight by three did not equalise release contributions. A corrected sensitivity pool uses observation-period fractions of 2/7.2, 3.2/7.2, and 2/7.2, following the CDC duration-weighting principle.
The reviewed check compares all 130 displayed quantiles, not only medians. Twelve rounded cells differ from the latest release by more than 0.02; the largest difference is 0.066. The latest release therefore remains primary and the period-adjusted pool is sensitivity evidence only.
Public age is top-coded at 80. The 80+ trend coordinate at age 85 is a display anchor, not a mean observed age. NHANES measures waist at the iliac crest; a ratio calculated from another waist landmark is not directly comparable. See the reference page for the remaining limitations.