IESET.
Hypotheses·distribution·tax_inequality_clinton_1993_obra_top_bracket

The 1993 Omnibus Budget Reconciliation Act (OBRA-1993), which raised the US top marginal income tax rate from 31 to 39.6 percent and added the 36 percent bracket, produced a transitory dip in the reported top-1 pre-tax income share via timing-shifted realisations into 1992, but no persistent level reduction in the top share by 1996 once the realisation pull-forward unwinds.

The discriminating test is whether the post-1993 trend slope of the top-1 share differs from the pre-1993 slope.

PARTIALengine/runs/tax_inequality_clinton_1993_obra_top_bracket

PARTIAL — shape=ITS, opposite sign but small (mean_gap=-1.031, z=-1.2)

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. shape=ITS, opposite sign but small (mean_gap=-1.031, z=-1.2)

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 1 country or place units from 1985 to 2000, using a event study design, with fixed effects for year.

what was measured
What changed
  • Obra 1993 post indicator
  • Realisation pullforward 1992
What we checked
  • Top 1pct pretax income 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_clinton_1993_obra_top_bracket
1007550250198519932000USA
illustrative sketch · run pending
No coefficients yet. When the model fires, this chart will show top_1pct_pretax_income_share across 1 sampled countries over 1985–2000.
The shapes above are stylised — none of the lines are real data.
Placeholder for tax_inequality_clinton_1993_obra_top_bracket. Published chart will be generated from engine/runs/tax_inequality_clinton_1993_obra_top_bracket/chart_data.json.

Pre-registration

registration ordering unverified
first-spec commit 4c8ce8e · 2026-07-18T22:11:21Z
run generated · 2026-04-30T12:29:39Z
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 1993 Omnibus Budget Reconciliation Act (OBRA-1993), which raised the US top marginal income tax rate from 31 to 39.6 percent and added the 36 percent bracket, produced a transitory dip in the reported top-1 pre-tax income share via timing-shifted realisations into 1992, but no persistent level reduction in the top share by 1996 once the realisation pull-forward unwinds. The discriminating test is whether the post-1993 trend slope of the top-1 share differs from the pre-1993 slope.

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

SUPPORTED if the post-1993 top-1 share trend slope (1994-1996) is within 0.10pp/yr of the pre-1993 slope (1989-1992) AND the 1992 spike is statistically significant at p<0.10. REFUTED if post-1993 slope is more than 0.20pp/yr below pre-1993 slope at p<0.10.

formal test & threshold
test:      US time-series structural-break test on top-1 share with explicit 1992 realisation-spike dummy.

Method

Template
event_study
Fixed effects
year
Clustering
year
Sample
1 countries · 1985 – 2000
Evidence type
associational

Event study with break at 1993Q3 + explicit 1992 pull-forward dummy. Newey-West HAC SEs.

Data

VariableSourceTransform
top_1pct_pretax_income_share
outcome
owid:top-1-share-of-total-incometier 2
level
obra_1993_post_indicator
treatment
constructed:indicator = 1 for year >= 1994tier 5
indicator
realisation_pullforward_1992
treatment
constructed:indicator = 1 for year == 1992tier 5
indicator
top_marginal_income_tax_rate
treatment
owid:top-marginal-income-tax-ratetier 2
level
log_real_gdp
control
fred:GDPC1tier 1
log
equity_index_real_yoy
control
fred:SP500tier 1
real_yoy_pct_change

● ready  · ● pending  · ● reconstruct-needed

Detailed result card

Result card — tax_inequality_clinton_1993_obra_top_bracket

Verdict: PARTIAL — shape=ITS, opposite sign but small (mean_gap=-1.031, z=-1.2)

Pre-registration

  • Claim: The 1993 Omnibus Budget Reconciliation Act (OBRA-1993), which raised the US top marginal income tax rate from 31 to 39.6 percent and added the 36 percent bracket, produced a transitory dip in the reported top-1 pre-tax income share via timing-shifted realisations into 1992, but no persistent level reduction in the top share by 1996 once the realisation pull-forward unwinds. The discriminating test is whether the post-1993 trend slope of the top-1 share differs from the pre-1993 slope.
  • Falsification rule: SUPPORTED if the post-1993 top-1 share trend slope (1994-1996) is within 0.10pp/yr of the pre-1993 slope (1989-1992) AND the 1992 spike is statistically significant at p<0.10. REFUTED if post-1993 slope is more than 0.20pp/yr below pre-1993 slope at p<0.10.
  • Falsification test: US time-series structural-break test on top-1 share with explicit 1992 realisation-spike dummy.
  • Event year: 1993

Estimate

  • shape: single_country_its
  • country: USA
  • event_year: 1993
  • n_pre: 8
  • n_post: 8
  • pre_trend_slope: 0.34654761904760994
  • pre_trend_intercept: -675.3061904761724
  • pre_residual_sd: 0.8724339438573954
  • end_year: 2000
  • end_year_actual: 17.34
  • end_year_counterfactual: 17.789047619047437
  • end_year_gap: -0.4490476190474375
  • mean_post_gap: -1.031130952380822
  • z_end: -0.5147067261757494
  • z_mean: -1.1819014604380944
  • post_period_years: [1993, 2000]

Variables resolved

  • owid:top-1-share-of-total-income → top_1pct_pretax_income_share (outcome, publisher=owid, n=3294)
  • owid:top-marginal-income-tax-rate → top_marginal_income_tax_rate (treatment, publisher=owid, n=590)
  • fred:GDPC1 → log_real_gdp (controls, publisher=fred, n=79)
  • fred:SP500 → equity_index_real_yoy (controls, publisher=fred, n=11)

Variables missing data

  • constructed: indicator = 1 for year >= 1994 (treatment, name=obra_1993_post_indicator)
  • constructed: indicator = 1 for year == 1992 (treatment, name=realisation_pullforward_1992)

Generated by scripts/run_event_study.py at 2026-04-30T12:29:39+00:00

Notes

Tax-inequality candidate, swarm-S6 batch 1. Tests Saez-Slemrod-Giertz ETI pull-forward story against a persistent-distortion alternative.

Authored framework. Read the transparency note.