Marker explorer
Altitude against value for each marker, with the hazard-shape zones shaded and the share of people in each zone.
Curve source:
Shaded band: the curve's confidence interval. Altitude is relative to the marker's median.
Where people are held on this curve
Dots on the curve mark stable points from the same people followed over the years (ELSA): levels that people in one sex and age group drift back to. Filled: passes every check, including the laboratory check. Ringed: a candidate. Grey: dropped because a laboratory change made it. A stable point need not sit in the trough; people can be held on a slope. The curve is fitted on men and women together (adjusted for sex), so for a marker that runs lower in women, such as haemoglobin, a women's point below the trough partly reflects that. See Stability.
A zone marked rises to the edge of the data keeps climbing as far as the data go. With a four-knot restricted cubic spline this is partly built in: the spline is forced to be straight beyond its outer knots, so it cannot bend back into a plateau. The flexible refit below is the test of that.
Zones
Share of people in each zone, by sex and age band
Shares use the marker's NHANES percentile table, from a single recent survey cycle, so they describe that cycle's population. They are not shown for grip strength, whose percentile table measures a different grip score from the curve.
Flexible-fit check
Each curve refitted on a penalised B-spline that can bend near the edges. A plateau counts only if the flexible fit has it, it clears the nadir's confidence interval, the fit converged with its penalty inside the search grid, and the flexible fit beats the four-knot spline on AIC.