Age-Gap Dynamics & Demographic Matrix

Clicking the '1970 Traditional' preset button sets autonomy to 0.38, female first-marriage age to 20.8 years, education ratio to 0.68, and the underlying preset longevity gap to 7.6 years (the visible slider renders at its maximum limit of 7.5 years). In calculateMetrics(), every parameter difference matches its baseline offset of 0, yielding an Older Woman Share of 6.4% and a Median Age Delta of +2.6 years. The Symmetry Index evaluates to 0.29, Autonomy Velocity displays 'Static', and the D3 distribution curve shifts rightward with a dashed amber ghost line matching the baseline.

The U.S. Census Bureau maintains official historical marital status series, including 'Table MS-2: Estimated Median Age at First Marriage, by Sex: 1890 to Present'. While the Census Bureau publishes these longitudinal demographic tables, the specific linear combinations, scaling constants, and media trope classifications implemented on this page are educational modeling fixtures rather than official federal census tables. Historical Marital Status Tables

The density curve evaluates gap values x from -15 to +20 years with step 0.5 using a Gaussian probability density function centered at the computed median gap, scaled by a standard deviation sigma = 3.8 + (olderWomanShare / 15). For negative gaps (where the woman is older), an exponential boost factor expands the tail. The resulting points are converted to SVG paths using D3's area generator (d3.area) with a baseline set to the inner chart height. Areas | D3 by Observable

• Historical Marital Status Tables

  Confirms the publication of Table MS-2 (Estimated Median Age at First Marriage, by Sex: 1890 to Present) by the U.S. Census Bureau.

• Areas | D3 by Observable

  Documents D3 area path generation bounded by a topline and baseline coordinate mapping.

The saved default inputs point eight two autonomy, age twenty eight point six, education ratio one point three five and longevity gap five point four give additive contributions seven point two six, five point zero seven, three point four eight four and one point seven six. Adding baseline six point four gives twenty three point nine seven four, displayed twenty four percent. Bars use fourteen pixels per percentage point. The coefficients are source assumptions. They do not demonstrate actual demographic prevalence, empirical regression validity or individual relationship outcomes. The saved median formula starts at two point six years and subtracts autonomy contribution point seven nine two, marriage age contribution point six two four and education contribution point three three five. It gives point eight four nine, rounded to point eight years. Bars use one hundred forty pixels per year. Longevity does not enter this median equation. Symmetry uses the unrounded share divided by fifty times two point three and is separately clamped between point two and point nine eight. The source does not establish a causal social model or a prescription for partner choice. The chart takes the rounded median and share. Its spread is three point eight plus share twenty four divided by fifteen, or five point four years. Bars use sixty five pixels per spread year. Seventy one points cover minus fifteen to plus twenty by half year steps. Negative gaps get an extra exponential boost, then the whole sampled density is normalized using the half year step to total one hundred. That operation does not explicitly force the negative area to equal the headline older woman share. JSON exports both headline metrics and sampled curve. Treat them as synthetic source outputs rather than verified census findings.