IESET.
Hypotheses·distribution·tax_inequality_france_1981_wealth_tax_top_share

The 1981 Mitterrand wealth tax (Impot sur les Grandes Fortunes, suspended 1986, reinstated 1988 as ISF) produced a measurable but modest reduction in the French top-1 wealth share over 1981-1985 relative to the synthetic control of comparable continental European economies, with capital-flight attrition smaller than the Macron-era political narrative implied.

The discriminating test is the synth-control gap on top-1 wealth share at five-year horizon.

INCONCLUSIVEengine/runs/tax_inequality_france_1981_wealth_tax_top_share

INCONCLUSIVE_DATA_PENDING — insufficient pre-period coverage (years=6, donors=0)

confidence cueResult card produced; verdict unclassified.

policy briefCoverage too thin

In ordinary language

In plain terms, this asks whether igf 1982 fra post is actually linked to better or worse top 1pct wealth share from 1975 to 1990.

plain answer

This test cannot make a firm call yet. insufficient pre-period coverage (years=6, donors=0)

why it matters

Distributional claims often sound morally clear but are empirically complex. This test asks whether the proposed channel explains real differences across places.

how the test works

It compares 7 country or place units from 1975 to 1990, using a synthetic control design, with fixed effects for country and year.

what was measured
What changed
  • Igf 1982 fra post
What we checked
  • Top 1pct wealth share
  • Top 10pct wealth share
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/tax_inequality_france_1981_wealth_tax_top_share
1007550250197519831990FRADEUITABELNLDAUTCHE
illustrative sketch · run pending
No coefficients yet. When the model fires, this chart will show top_1pct_wealth_share across 7 sampled countries over 1975–1990.
The shapes above are stylised — none of the lines are real data.
Placeholder for tax_inequality_france_1981_wealth_tax_top_share. Published chart will be generated from engine/runs/tax_inequality_france_1981_wealth_tax_top_share/chart_data.json.

Pre-registration

registration ordering unverified
first-spec commit 4c8ce8e · 2026-07-18T22:11:21Z
run generated · 2026-05-04T12:34:34Z
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.

The 1981 Mitterrand wealth tax (Impot sur les Grandes Fortunes, suspended 1986, reinstated 1988 as ISF) produced a measurable but modest reduction in the French top-1 wealth share over 1981-1985 relative to the synthetic control of comparable continental European economies, with capital-flight attrition smaller than the Macron-era political narrative implied. The discriminating test is the synth-control gap on top-1 wealth share at five-year horizon.

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

SUPPORTED if French top-1 wealth share falls by at least 1 percentage point relative to synthetic-control trajectory over 1981-1985 AND the pre-treatment fit RMSPE is below post-treatment by a factor of 2. REFUTED if no detectable gap (within 0.3pp) at five-year horizon or pre/post RMSPE ratio fails the placebo test.

formal test & threshold
test:      Synthetic control with continental European donor pool (DEU, ITA, BEL, NLD, AUT, CHE), treated FRA 1982. Outcome top-1 wealth share.

Method

Template
synthetic_control
Fixed effects
country, year
Clustering
country
Sample
7 countries · 1975 – 1990
Evidence type
associational

Synthetic-control with continental EU donor pool. Treated FRA 1982. Placebo-in-time at 1979 + placebo-in-space across donor pool.

Data

VariableSourceTransform
top_1pct_wealth_share
outcome
owid:top-1-share-of-total-wealthtier 2
level
top_10pct_wealth_share
outcome
owid:top-10-share-of-total-wealthtier 2
level
igf_1982_fra_post
treatment
constructed:indicator = 1 for FRA, year >= 1982tier 5
indicator
log_real_gdp_per_capita
control
world_bank_wdi:NY.GDP.PCAP.KDtier 2
log
trade_openness
control
world_bank_wdi:NE.TRD.GNFS.ZStier 2
level
cpi_inflation
control
world_bank_wdi:FP.CPI.TOTL.ZGtier 2
level

● ready  · ● pending  · ● reconstruct-needed

Detailed result card

Result card — tax_inequality_france_1981_wealth_tax_top_share

Verdict: INCONCLUSIVE_DATA_PENDING — insufficient pre-period coverage (years=6, donors=0)

Pre-registration

  • Claim: The 1981 Mitterrand wealth tax (Impot sur les Grandes Fortunes, suspended 1986, reinstated 1988 as ISF) produced a measurable but modest reduction in the French top-1 wealth share over 1981-1985 relative to the synthetic control of comparable continental European economies, with capital-flight attrition smaller than the Macron-era political narrative implied. The discriminating test is the synth-control gap on top-1 wealth share at five-year horizon.
  • Falsification rule: SUPPORTED if French top-1 wealth share falls by at least 1 percentage point relative to synthetic-control trajectory over 1981-1985 AND the pre-treatment fit RMSPE is below post-treatment by a factor of 2. REFUTED if no detectable gap (within 0.3pp) at five-year horizon or pre/post RMSPE ratio fails the placebo test.

Synthetic-control estimate

  • Error: insufficient pre-period coverage (years=6, donors=0)

Variables resolved

  • owid:top-1-share-of-total-wealth → top_1pct_wealth_share (outcome, n=10811)
  • owid:top-10-share-of-total-wealth → top_10pct_wealth_share (outcome, n=10811)
  • constructed: indicator = 1 for FRA, year >= 1982 → igf_1982_fra_post (treatment, n=112)
  • world_bank_wdi:NY.GDP.PCAP.KD → log_real_gdp_per_capita (controls, n=14066)
  • world_bank_wdi:NE.TRD.GNFS.ZS → trade_openness (controls, n=10714)
  • world_bank_wdi:FP.CPI.TOTL.ZG → cpi_inflation (controls, n=9066)

Generated by scripts/run_synth_did.py at 2026-05-04T12:34:34+00:00

Notes

Tax-inequality candidate, swarm-S6 batch 2. Tests the canonical "wealth tax causes capital flight" narrative against the early French case pre-CRS-era.

Authored framework. Read the transparency note.