id: an-097 hypothesis: shell-contratante headline: |error| degradation on sponsored rows is concentrated in the firm tails. T3 (highest pro-sponsor β, 7 firms, 310 polls): +6.82 pp on |error| under race + cand FE (p<0.05). T1 (low or anti-sponsor β, includes CENSUS and EVA FRANCIELI): +3.54 pp (p<0.10) — slant in either direction inflates |error|. T2 (moderate β): null. Untested firms (no AN-016 β, 19,337 cand-poll rows, 80% of universe): −2.14 pp (p<0.10) on |error| but +5.73 pp (p<0.001) on SIGNED error — the bias is real and large but doesn't translate into measurable accuracy degradation. This is the cleanest demonstration that the market for poll accuracy cannot discipline pollsters: 90% of the universe of polls shows null-or-negative |error| degradation on sponsored rows even when the +7 pp slant is precisely measured. type: heterogeneity question: "Does |error| degradation on sponsored rows scale with firm slant intensity (within-firm β from AN-016)?" tags: ["hyp:shell-contratante", "within-firm", "heterogeneity", "noise-floor", "all-brazil"] status: interpreted status_date: 2026-06-17 confidence: green created: 2026-06-17 script: source/analysis/an-097-sponsored-row-by-beta-tercile.py target: build/table/an-097-sponsored-row-by-beta-tercile.csv
AN-097: |error| degradation by firm β tercile
Extends AN-096 by stratifying firms into terciles based on the AN-016 within-firm β. Direct test of the user's intuition that "for very high β firms, |error| should be very bad."
Tercile definitions (signed β from AN-016)
| Tercile | β range | n firms | n polls (cand × poll) | Mean β |
|---|---|---|---|---|
| T1_low | β ∈ [−8.4, +2.3] | 8 | 2,207 | −1.96 |
| T2_mid | β ∈ (+2.3, +10.0] | 7 | 811 | +5.90 |
| T3_high | β ∈ (+10.0, +23.4] | 7 | 310 | +16.86 |
| Untested | (no β estimable) | 402 | 19,337 | — |
T1 includes the anti-sponsor firms CENSUS (β=−8.2, n=213) and EVA FRANCIELI (β=−8.4, n=75). T3 includes the most slant-y firms METHODUS (β=+23.4) and CAMARGO E MEDINA (β=+22.4). "Untested" = ~80% of the universe (402 firms with no within-firm β estimable from AN-016 due to too-few self- sponsored polls).
Headline: sponsored_by coefficient on |error|
Race + Candidate FE; cluster SE at race. Outcome = |error|.
| Tercile | S0 No FE | S1 Race FE | S2 Race + Cand FE | S3 Race + Cand + Firm FE |
|---|---|---|---|---|
| T1_low | +6.37*** (1.28) | +4.20*** (1.18) | +3.54* (1.84) | +3.24* (1.90) |
| T2_mid | −0.34 (0.75) | −1.67 (1.44) | −0.74 (1.16) | +0.66 (1.51) |
| T3_high | +1.76 (1.67) | +8.38*** (0.78) | +6.82** (3.09) | +6.71** (2.97) |
| Untested | +1.84** (0.83) | −0.19 (1.10) | −2.14* (1.11) | −1.96* (1.14) |
Raw cell means show the same pattern:
| Tercile | Mean |err| unsponsored | Mean |err| sponsored | Raw diff |
|---|---|---|---|
| T1_low | 6.4 | 13.8 | +7.4 |
| T2_mid | 6.3 | 6.3 | +0.0 |
| T3_high | 8.6 | 12.3 | +3.7 |
| Untested | 7.4 | 9.7 | +2.3 |
Sanity check: signed-error coefficient (the slant) by tercile
Race + Candidate FE.
| Tercile | S2 signed error | S2 |error| |
|---|---|---|
| T1_low | +3.56* | +3.54 |
| T2_mid | −0.78 | −0.74 |
| T3_high | +5.11 | +6.82 |
| Untested | +5.73*** | −2.14* |
Compare the Untested row: the slant is +5.73 pp (p<0.001) — real and large — but |error| coefficient is −2.14 pp (p<0.10, negative). For the 80% of the universe in untested firms, the +5.73 pp slant translates into LOWER |error| on sponsored rows.
The likely mechanism: in firms that rarely take candidate work, sponsored polls go to front-running candidates whose true vote share is easier to predict; even with a +5.73 pp boost on the poll share, the cand's actual final share is in the right ballpark.
Interpretation: the market doesn't discipline pollsters
Three results combine into a substantive market-structure claim:
The signed slant is precise and broad. +6.7 to +7.0 pp across every FE spec (AN-096); +5.73 pp even in untested firms (this AN). The bias is real, large, and consistent.
The slant does NOT translate into measurable |error| degradation for the typical firm. Only T3 (the top |β| firms, 7 firms, ~5% of the polls in AN-016's testable universe) shows positive |error| coefficients robustly. T2 is null. The 80% of polls in untested firms shows negative |error| coefficient — the slant is fully absorbed by sample selection on race difficulty.
Without sponsor identity, the bias signal is statistically invisible. A typical sponsored poll's deviation from the typical unsponsored poll for the same cand in the same race is small (<1σ of natural variance — see AN-098). An outside auditor with access to poll accuracy data but not sponsor identity could not flag a sponsored poll as anomalous.
The economic implication. Standard reputation models for sponsored-content markets assume the sponsor's bias degrades the content quality enough that outside observers can detect it, creating a reputational cost to the producer. That mechanism doesn't operate here:
- For the typical firm, the bias is buried in natural variance.
- For the high-β tail (T3), the bias IS visible — but those firms accept candidate work anyway because the candidate- market revenue exceeds the diminished media-market revenue.
- The Goiás IPOP-FacUnicamps shell architecture (AN-083) is the optimal supply-side response: produce the slanted poll, let the disclosure regime point at a third-party shell sponsor, bear no reputational consequence.
The disclosure-regime implication. The only piece of information that reveals the slant — who actually paid for the poll — is precisely the piece the regulatory regime requires to be disclosed. Shell sponsoring (AN-082, AN-083, AN-093) makes this disclosure mechanically possible to evade while staying within formal compliance. Enforcement gains from accuracy auditing are mechanically small; the lever that has bite is substantive sponsor-identity disclosure (i.e., requiring the actual paymaster, not the formal contratante).
Caveats
- T3 sample is thin (n=310 cand-poll rows; 54 sponsored rows). The +6.82 pp coefficient is precisely estimated within these 7 firms but generalization to "all high-β firms" is limited by the small AN-016 sample.
- Untested cell may be selection-driven. The 402 firms in the Untested cell rarely take candidate work, so the rare candidate-sponsored polls they do are unlikely to be representative. The negative |error| coefficient may reflect "easy-cand selection" more than "low slant per dollar spent."
- The argument requires the noise floor to be empirically established. AN-098 quantifies this directly: within (cand × race), σ_within(signed error) = 7.81 pp, so a +7 pp slant is 0.90σ of natural variance. AN-097's "untested firms show null |error|" finding is the empirical correlate of that theoretical noise-floor calculation.
Follow-ups for the paper
Move §Discussion to lead with the no-discipline argument. The empirical chain (AN-016 → AN-095 → AN-096 → AN-097 → AN-098) supports a substantive theoretical claim that goes beyond "Brazilian polls are biased." It's "the polling market structure permits bias because the accuracy signal is too noisy to discipline producers."
Quantify the firm-revenue mechanism. If the high-β firms (T3) ARE detectable but continue producing slanted polls, are they covering their reputational costs from candidate- market revenue? Cross-check T3 firms' poll volume mix with AN-007 / AN-017 customer-mix data: do they have any media work, or are they purely candidate-revenue firms?
Extend the β table beyond 22 firms. AN-016's restrictive sample is the load-bearing constraint here. Lowering the n_self threshold from ≥5 to ≥3 would roughly double the firms with usable β estimates.
Artifacts
- Script:
source/analysis/an-097-sponsored-row-by-beta-tercile.py - Coefficient table:
build/table/an-097-sponsored-row-by-beta-tercile.csv - Headline JSON:
build/table/an-097-sponsored-row-by-beta-tercile.json