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AN-022: Pregão-only falsification

Intuition (plain-language)

Does the FL-price relationship hold across modalities, and is it the same size? Same direction, very different magnitude: binary FL raises prices +9.6% in Pregão vs +3.9% in Convite (2.45× larger), and the joint specification flips the binary sign altogether. The magnitude asymmetry is again scope — it tells you where the FL-price association concentrates — not a clean modality-specific damages estimate you could bank.

Question

Do FL-margin price effects differ by procurement modality, and does the Pregão-only subsample replicate the full-sample direction? The test isolates the modality contribution from the cross-modal scope variation in AN-016.

Design

  • Sample: BEC items 2009–2019:
  • Pregão: N = 543,752;
  • Convite: N = 1,105,852;
  • Full: N = 1,653,658.
  • Specifications:
  • Binary FL presence indicator;
  • Continuous log(1 + tenders_count);
  • Joint binary + continuous.
  • Fixed effects: item, year, PBU.
  • SE: item-clustered.

Results

Single-score specifications (binary):

Sample Coefficient SE p
Pregão only +0.0959*** 0.0256 < 10⁻³
Convite only +0.0392** 0.0188 0.037
Full sample +0.0653*** 0.0216 0.003

Pregão/Convite ratio: 2.45×.

Single-score specifications (continuous):

Sample Coefficient SE p
Pregão only +0.0262*** 0.0063 < 10⁻⁴
Convite only +0.0124** 0.0049 0.011

Pregão/Convite ratio: 2.11×.

Joint specifications (binary + continuous):

Sample Binary coef SE Continuous coef SE
Pregão only −0.0652 0.0449 +0.0399*** 0.0118
Convite only −0.0828** 0.0350 +0.0305*** 0.0101

Macros: \valFalBinPregCoef, \valFalBinConvCoef, \valFalBinFullCoef, \valFalBinRatio, \valFalContPregCoef, \valFalContConvCoef, \valFalContRatio, plus the \valFalJoint* series.

AN-022 modal falsification — Pregão 2.45× Convite

Figure: FL-margin coefficient on log price across four modality × score cells, with 95% CIs. Pregão binary +0.096 vs Convite binary +0.039; Pregão continuous +0.026 vs Convite continuous +0.012. Pregão coefficient ~2× larger than Convite in both binary and continuous specs.

Interpretation

The modal asymmetry from D2 (AN-016) replicates in the price equation: Pregão coefficients are ~2× larger than Convite across both binary and continuous specs. The asymmetry is robust to modality-restriction.

In the joint specifications, the binary coefficient flips negative in both modalities — the continuous score absorbs the persistent-loss signal, leaving the binary picking up a residual that flips sign. This sign reversal under joint specification is the same pattern as in AN-015 and is part of the scope-vs-damages evidence (H:price-scope-sign-reversal).

The cross-modal direction (Pregão > Convite) is reported as scope information — telling us where the loser-side ranking applies more strongly — not as a positive test of an institutional minimum-bidder- rule theory (per the locked rule from D2).

Follow-ups

  • Sub-period sensitivity within each modality.
  • Convite-only counterpart with small-N power diagnostic.
  • Cross-sector decomposition (commodities vs services from script 52).