How We Compute Chain Attribution

Methodology for the PAC chain attribution figures shown on entity profiles

What Chain Attribution Is

Money in federal elections often does not travel in a straight line. A donor gives to a PAC, that PAC transfers money to another PAC, and the second PAC spends on behalf of a candidate. Each individual transaction is reported to the Federal Election Commission, but no filing connects the donor at the start of the chain to the candidate at the end. Chain attribution is our method for estimating those end-to-end connections from the individual reported transactions.

Every chain shown on the site is built entirely from transactions that committees themselves reported to the FEC. The chains are factual records of money movement between committees. They are not evidence of donor intent, coordination, or any agreement between the parties involved.

The Data

The inputs are itemized transactions from FEC filings, classified by their FEC transaction type code into three roles.

Origin transactions (codes 11a and 11c) are contributions from individuals or organizations entering the committee network. These are the donors at the start of a chain.
Transfer transactions (codes 22Y and 22Z) are committee-to-committee transfers. These are the intermediate hops.
Terminal transactions (the 24-series, including 24K direct contributions, 24A and 24E independent expenditures, and 24T earmarked conduit contributions) are where money reaches a candidate or is spent for or against one. These are the ends of chains.

The Algorithm

We start at each terminal transaction and walk backward. The PAC that made the terminal payment received money from many sources, so we apportion the terminal amount across its inflows in proportion to each inflow's share of the total. If an inflow is itself a transfer from another PAC, we repeat the process one level up, continuing until we reach an origin contribution or hit the hop cap.

Date ordering. When apportioning a payment made on a given date, we only count inflows dated on or before that date, because money cannot be spent before it arrives. When dates are missing, or no recorded inflows precede the payment, we fall back to apportioning across all of the committee's inflows for the cycle. Chains built with that fallback are flagged on the site (“date order unverified”) and are always assigned low confidence.

Hop cap. Chains are capped at five hops. Beyond that depth, proportional apportionment dilutes amounts to the point where the estimate is no longer meaningful, so longer routes are not traced.

Cross-cycle flag. If a committee spent noticeably more in a cycle than it took in, some of its spending was likely funded by cash on hand from an earlier cycle. Chains through such committees carry a cross-cycle flag, because part of the money may predate the inflows we apportioned it across.

What the Numbers Mean

Each chain carries two numbers, and they mean different things.

The attributed amount, labeled “modeled estimate,” is the output of the proportional apportionment described above. It is an estimate of how much of the terminal spending traces back to a given origin donor. It is not a reported transaction, and no FEC filing contains that dollar figure. Because dollars are fungible once they enter a committee's account, no method can determine which specific dollars funded which specific payment; proportional apportionment is a standard, transparent convention for estimating it.
The documented floor, shown as “at least $X documented end-to-end,” is the smallest single transaction along the chain. Every leg of the chain is an actual FEC-reported transaction of at least that size, so that amount is the conservative, provable lower bound on what is documented along the route.

Attributed amounts are estimates of flow, not reported transactions. Where a precise reported figure matters, use the documented floor or follow the source links to the underlying FEC filings.

Confidence Levels

High. Both the origin donor and the terminal recipient are matched to official FEC committee or candidate IDs, the chain is short, and date ordering was enforced at every hop. Entity identification is deterministic, not name-based.
Medium. The chain is sound but at least one endpoint was matched by name rather than by FEC ID, so there is some chance the entity resolution is wrong.
Low. One or more of the following: the chain is at or near the five-hop cap, the backward walk stopped at the cap before reaching a true origin contribution, or date ordering could not be enforced and the cycle-wide fallback was used.

Limits of the Method

Chain attribution covers only money movements itemized in FEC filings. It does not capture unitemized small-dollar contributions, spending by organizations that do not report to the FEC, or non-financial relationships. Chains describe where money moved, in what order, and in what reported amounts. They do not establish why a donor gave, whether a donor knew where the money would end up, or any quid pro quo.

Corrections are welcome. If you believe a chain misstates the underlying filings, contact us and we will review it against the FEC record.