IESET.
Hypotheses·welfare architecture·welfare_transfer_korea_eitc_2009_labour_supply_effect

South Korea's Earned Income Tax Credit (EITC, introduced 2009 with subsequent expansions 2012, 2015, 2019) raised labour-force-participation among low-income married women by 2 to 4 percentage points within five years of each expansion threshold change, identified off discontinuity in eligibility-cliff income brackets across years using a regression-discontinuity-in-time framework consistent with US EITC literature (Eissa-Liebman 1996; Hoynes-Patel 2018).

PARTIALengine/runs/welfare_transfer_korea_eitc_2009_labour_supply_effect

PARTIAL - national female LFP rose 2.3pp by 2014, matching the 2-4pp band, but the low-income married-women RD design is not loaded

confidence cueThe result is useful, but not decisive. Treat it as a clue, not a settled conclusion.

policy briefMixed or noisy

In ordinary language

Over a long period, do more market-oriented institutions translate into higher income or productivity, once the comparison looks beyond a single success story?

plain answer

The evidence is suggestive but not decisive. national female LFP rose 2.3pp by 2014, matching the 2-4pp band, but the low-income married-women RD design is not loaded

why it matters

This matters because welfare architecture claims should change belief only when they survive a pre-declared empirical test.

how the test works

It compares 1 country or place units from 2005 to 2022, using a event study design, with fixed effects for household and year.

what was measured
What changed
  • Eitc eligibility indicator
What we checked
  • Female lfp low income married
  • Hours worked low income women
what this does not prove

A single test is not the whole truth. It narrows the claim under a specific sample, time period, and method. Strong policy conclusions need the pattern to survive nearby tests, alternative data, and serious objections.

verification

No evidence packet has been generated yet.

Results

engine/runs/welfare_transfer_korea_eitc_2009_labour_supply_effect
1007550250200520142022KOR
illustrative sketch · run pending
No coefficients yet. When the model fires, this chart will show female_lfp_low_income_married across 1 sampled countries over 2005–2022.
The shapes above are stylised — none of the lines are real data.
Placeholder for welfare_transfer_korea_eitc_2009_labour_supply_effect. Published chart will be generated from engine/runs/welfare_transfer_korea_eitc_2009_labour_supply_effect/chart_data.json.

Pre-registration

pre-registered
first-spec commit 098ce96 · 2026-04-30T12:57:33Z
run generated · 2026-05-18T19:35:52Z

South Korea's Earned Income Tax Credit (EITC, introduced 2009 with subsequent expansions 2012, 2015, 2019) raised labour-force-participation among low-income married women by 2 to 4 percentage points within five years of each expansion threshold change, identified off discontinuity in eligibility-cliff income brackets across years using a regression-discontinuity-in-time framework consistent with US EITC literature (Eissa-Liebman 1996; Hoynes-Patel 2018).

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

Refuted if the post-expansion ATT on female-LFP among eligible low-income married women is below +2pp at five-year horizon, OR if the 95% CI excludes +2pp, OR if a placebo eligibility-cap discontinuity in non-expansion years also produces comparable ATT.

formal test & threshold
test:      event_study_5yr_lfp_eligible_low_income_married_women
threshold: ATT >= +2pp at 5yr horizon AND lower 95% CI bound > 0

Method

Template
event_study
Fixed effects
household, year
Clustering
household
Sample
1 countries · 2005 – 2022
Evidence type
causal

Event study around 2009 introduction and 2012, 2015, 2019 expansion thresholds. RD-in-time framework using bracket-cap discontinuities. Robustness: comparison-cohort with secondary-earner households just above eligibility threshold.

Data

VariableSourceTransform
female_lfp_low_income_married
outcome
oecd:DSD_LFS_BStier 2
level_pct
hours_worked_low_income_women
outcome
oecd:DSD_LFS_BStier 2
level
eitc_eligibility_indicator
treatment
oecd:DSD_LFS_BStier 2
indicator
gdp_per_capita_real
control
world_bank_wdi:NY.GDP.PCAP.KDtier 2
log
minimum_wage_relative_median
control
oecd:DSD_EARNINGStier 2
level

● ready  · ● pending  · ● reconstruct-needed

Detailed result card

Result card - welfare_transfer_korea_eitc_2009_labour_supply_effect

Verdict: PARTIAL - national female LFP rose 2.3pp by 2014, matching the 2-4pp band, but the low-income married-women RD design is not loaded

Exact Local Benchmark

  • Female LFP rose 2.3 pp from 2009 to 2014.
  • Female LFP rose 4.2 pp from 2009 to 2019 across later EITC expansions.
  • Total employment-to-population rose 2.2 pp from 2009 to 2014.

Caveats

  • The local proxy is national female LFP, not low-income married-women eligibility-bracket microdata.

Sources

  • world_bank_wdi:SL.TLF.CACT.FE.ZS -> female_lfp_proxy (data/vintages/world_bank_wdi/SL.TLF.CACT.FE.ZS@2026-05-05T194807Z.parquet)
  • world_bank_wdi:SL.EMP.TOTL.SP.ZS -> employment_to_population (data/vintages/world_bank_wdi/SL.EMP.TOTL.SP.ZS@2026-05-05T194751Z.parquet)

Generated by engine/runs/welfare_transfer_korea_eitc_2009_labour_supply_effect/replication.py at 2026-05-18T19:35:52+00:00

Strongest opposing argument

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

Authored framework. Read the transparency note.