South Korea experienced a "fertility cliff" 2…

South Korea experienced a "fertility cliff" 2015-2024 (TFR falling from ~1.24 to <0.8), globally unprecedented in peacetime.

The hypothesis predicts (a) Korea's TFR decline exceeds 3 standard deviations relative to OECD-comparator decadal changes, (b) the decline is concentrated in metropolitan/Seoul cohorts, and (c) early signals of working- age contraction are visible in 2020-2024 labour-market participation among 25-34 year olds.

Pre-registration

registration ordering unverified

first-spec commit 098ce96 · 2026-04-30T12:57:33Z

run generated · 2026-04-30T08:07:38Z

Run timestamp predates this path's first git-add commit (rebase, rename, or pre-git local run). Spec hash is still the path's first-add commit — not repository HEAD — but ordering is not a clean pre-registration proof.

South Korea experienced a "fertility cliff" 2015-2024 (TFR falling from ~1.24 to <0.8), globally unprecedented in peacetime. The hypothesis predicts (a) Korea's TFR decline exceeds 3 standard deviations relative to OECD-comparator decadal changes, (b) the decline is concentrated in metropolitan/Seoul cohorts, and (c) early signals of working- age contraction are visible in 2020-2024 labour-market participation among 25-34 year olds.

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

SUPPORTED if Korea's TFR change 2015-2024 is at least 3 SD below comparator-panel mean decadal change AND TFR end-point < 0.85. REFUTED if Korea is within 2 SD of comparators or TFR did not fall below 0.9.

formal test & threshold

test:      korea_tfr_zscore_against_comparator_panel
threshold: korea_tfr_zscore <= -3.0 AND korea_tfr_2024 < 0.85

Method

Template: descriptive
Sample: 10 countries · 2000 – 2024
Evidence type: descriptive

Time-series description of Korea TFR vs comparator panel; report decadal changes and z-scores against OECD comparator distribution. No causal claim; this is a pattern-recognition spec to anchor downstream causal hypotheses.

Data

Variable	Source	Transform
total_fertility_rate outcome	world_bank_wdi:SP.DYN.TFRT.INtier 2	level
birth_rate_crude outcome	world_bank_wdi:SP.DYN.CBRT.INtier 2	level
lfp_25_34_female outcome	ilostat:EAP_2WAP_SEX_AGE_RTtier 2	level
gdp_per_capita_ppp control	world_bank_wdi:NY.GDP.PCAP.PP.KDtier 2	log

● ready · ● pending · ● reconstruct-needed

Strongest opposing argument

Every hypothesis ships with its charitable opposing argument. The framework earns credibility by handling objections at their strongest, not weakest.