AN-003: CADE × BEC linkage and cobidder construction¶
Intuition (plain-language)
To grade a screen you need ground truth about who actually colluded. CADE, Brazil's antitrust authority, has adjudicated procurement cartels; matching defendants to BEC by CNPJ root yields 47 direct defendants. But direct defendants are the cartel's winners — the wrong target for a loser-side screen. The honest validation target is the 193 cobidders: always-loser firms that repeatedly bid alongside adjudicated cartelists. These are the cover-bidding roles the screen is built to rank, and the linkage fixes them before any performance number is computed.
Question¶
How are CADE direct defendants and adjudication-anchored cobidders linked to BEC firms via CNPJ root, and what is the resulting set used as the validation target?
Design¶
- Inputs:
- CADE procurement-cartel adjudications in 2009–2019 covering bid rigging in São Paulo procurement environments.
- BEC firm registry of 41,444 firms.
- Linkage: CNPJ-root match (first 8 digits of the 14-digit CNPJ).
- Cobidder construction: always-loser firms that bid in the same tender-items as direct CADE defendants in the adjudicated cartel environments; excludes direct defendants by construction.
Results¶
| Target | Count | Source |
|---|---|---|
| Direct CADE defendants linked to BEC | 47 | data/processed/cade_bec_crossmatch.csv |
| Cobidders (always-losers bidding alongside) | 193 | data/processed/cade_fl_cobidders.csv |
Macros: \valDirectCADE (47), \valCobidders (193). The 193 figure
corrects the prior 98 cobidders that resulted from a CNPJ zero-pad bug
documented in the v12 forensic audit
(work/v12/paper_v12.pdf), and locked from v13 onward.
Interpretation¶
The 193 cobidders define the legally limited validation target: an adjudication-anchored footprint of always-loser firms that the loser-side rank can plausibly cover. The 47 direct defendants are the disconfirming target — the loser-side rank should not discriminate them (see H:direct-defendants-null and AN-007). The cobidder set is the construct that anchors all downstream baseline, exposure, timing, and leakage audits.
Follow-ups¶
- Sensitivity to CNPJ-root (first 8 digits) vs full CNPJ matching.
- Decomposition of cobidders by adjudication-anchor sub-period.
- Update path when new CADE adjudications enter the panel.