How the Field Index sources, verifies, and curates every comp.

The disclaimer in full

The Field Index aggregates publicly reported memorabilia sales from auction-house catalogs, trade-press reporting, and grading-service population data. Figures shown reflect the publicly reported hammer + buyer's premium as of the cited source date and may differ from privately-recorded auction-house records. This is an educational reference, not an appraisal. Always verify directly with the auction house or grading service before relying on a comparable for valuation, insurance, or sale decisions.

Inclusion criteria

A sale is included in the Field Index when it satisfies all three criteria below.

1. Documentary completeness

Every comp must document: the auction venue (or named dealer), the lot number (or dealer-catalog reference), the sale date, the authentication grade or letter (where applicable), and the publicly-reported hammer + buyer's premium. A sale missing any of these elements is not eligible, even if reliable-sounding from secondary reporting.

2. Source independence

Every comp cites at least one source that is independent of the seller. The auction-house catalog by itself does not satisfy this — there must be a corroborating reference from one of: trade press (ESPN, Sports Collectors Daily, Variety, Rolling Stone, BBC, AP, Reuters), grading service population data (PSA, BGS, SGC, CGC, AFA, PCGS, NGC), government archive (FBI press releases, Library of Congress, National Archives), or recognized specialty publication (Eric King's Bill Graham catalog, Sullivan's political-collectibles catalog, Hake's cataloging history).

3. Category relevance

The Field Index covers the price band collectors actually encounter — not only the record-setting outliers. The Pre-1900s benchmark, the working-collector mid-tier, the recent record-setter, and the recent normalization data point are all category-relevant; an arbitrary one-off sale with no comparable in the category is not.

What gets excluded

• eBay sold listings without authenticator + chain-of-custody. The noise floor of eBay data is structurally too high for reliable comparable analysis. We include eBay sales only when the seller is a recognized authenticator or auction house.
• Reported private sales without independent verification. If a sale is reported only by the dealer or seller, with no auction house, no third-party authentication, and no trade-press coverage, it does not qualify.
• Sales prior to 2000 where source documents are not currently accessible. Pre-2000 historic sales (Aaron 715 ball, McGwire 70 ball, etc.) are included on a case-by-case basis where the original source documents remain publicly accessible.
• Sales that have been publicly contested or reversed. Where an authentication or sale has been later reversed or challenged by the parties or by an authenticator, the comp is removed pending resolution.

Source taxonomy

Each Field Index comp's source list is tagged with one of:

• auction-house — Source is the auction-house catalog or post-sale report. Always the primary record for an auction sale.
• trade-press — Independent reporting from a recognized trade or general-press outlet covering the sale.
• grading-service — Authentication or population data from a recognized service (PSA, JSA, Beckett, SGC, CGC, AFA, MeiGray, Resolution Photomatching, PCGS, NGC).
• dealer-catalog — For sales conducted through a recognized dealer with a published catalog (not a private retail sale).
• government-archive — FBI press releases, Library of Congress acquisitions, National Archives documents, court filings.

Refresh cadence

New comps are added each quarter, alongside the Field Index quarterly market-pulse report. Significant single sales — record-setters (above $5M or category records), category benchmarks (sales that re-price a working-collector tier), and high-profile sales of independent reporting interest — are added within 30 days of public reporting. The complete dataset is republished in January each year.

Editorial standards

Inclusion is editorial. Auction houses and dealers cannot pay for a listing. Memorabilia.co does not accept consideration in any form — financial, in-kind, or future-promise — in exchange for Field Index inclusion. Sales submitted by auction houses, dealers, or institutions go through the same inclusion criteria as sales we identify independently.

Where the editorial team disagrees about inclusion or categorization, the senior editor's decision is final and documented in the comp's editorial note. Categorical disputes are resolved with reference to: the seller's own catalog classification, the category convention used by the dominant authenticator in the segment, and the practical buyer cohort (who actually bid on the item).

Threshold levels

The Field Index uses category-specific inclusion thresholds:

• Trading cards: $5,000 hammer + premium. Below threshold, the long-tail volume produces noise that obscures useful trends.
• Memorabilia (sports, comics, music, movie/TV, toys): $10,000.
• Documents and props with documented chain-of-custody: $25,000.
• Autographs (standalone): $5,000.

Reported figures vs. internal records

Every figure shown in the Field Index reflects publicly-reported hammer + buyer's premium as of the source-cited date. These figures may differ slightly from the auction house's internal records — for several reasons including buyer-side premium adjustments, post-sale clearing, and reporting-vs-clearing delays.

Treat Field Index figures as directionally accurate for comparable-sale benchmarking, not as exact internal records. Always verify directly with the auction house before relying on a Field Index comp for valuation, insurance, or sale decisions.

How we handle correction requests

Where a sale is misreported, miscategorized, or where a buyer or seller wishes to dispute the public record, we welcome correction requests via the contact form. We update the Field Index entry within 14 days of receipt of supporting documentation. Material updates are logged in the comp's revision history (visible in the entry itself).