| map_nhanes_pa_quantiles | Map physical activity values to NHANES population quantiles |
| nhanes_measure_data | NHANES PA data |
| nhanes_pa_age_category | Convert ages to NHANES physical activity CDF age categories |
| nhanes_pa_quantile | Evaluate a single NHANES physical activity quantile |
| precompute_nhanes_pa_cdfs | Precompute and cache NHANES PA CDFs |