Data methodology
How OPData builds its market view
Every market number is an estimate built from an underlying source and a set of matching rules. This page explains what OPData measures, how records are assigned to individual printings, and where collectors should use caution.
Printing identity comes first
One Piece cards frequently share a card number while differing in artwork, finish, product, language, or distribution channel. OPData assigns a persistent printing identity to each catalog version. Raw price history, graded sales, gem rates, portfolio lots, and canonical card URLs use that identity whenever the source provides enough evidence.
When two possible printings cannot be distinguished safely, OPData prefers to leave the data unassigned instead of attaching a sale or population record to the wrong card. This precision-first rule means some pages may show fewer graded observations than a broad marketplace search.
Raw-card prices
Raw prices are supplied through JustTCG from TCGPlayer catalog and market data. OPData refreshes supported groups daily and stores history per printing, rather than combining every card with the same number. The displayed market price is a marketplace reference, not an appraisal of a particular physical copy.
Condition, language, seller reputation, shipping, taxes, local demand, and recent supply can all cause a real transaction to differ. Percentage changes compare stored snapshots; a newly mapped printing or a marketplace correction can create a sharp move that is not a broad change in collector demand.
Graded prices
Graded estimates are built from eBay sold listings. Candidate listings are checked for the card number, character, printing descriptors, grader, and numeric grade. Known sibling printings are rejected when the title does not contain enough evidence to distinguish them. Ambiguous matches are excluded.
Accepted observations are grouped by printing, grading company, grade, and time window. OPData uses medians rather than the latest sale because medians are less sensitive to a single unusually high or low result. Obvious outliers are trimmed, and the display selects the best supported recent window. A value based on a small sample should still be treated as directional evidence, not a guaranteed liquidation price.
Gem rates and populations
Population and gem-rate data comes from GemRate. OPData searches by card number and then compares names, sets, years, languages, and parallel descriptions before assigning a result to a printing. Results that collide across plausible printings are omitted rather than guessed.
A gem rate is the share of the matched population receiving the highest tracked grade. It does not measure the chance that a randomly opened copy will gem. Submission selection, grading standards, resubmissions, cleaning, and small populations all introduce bias. Population reports also change as grading companies process new submissions.
Sold activity and liquidity
Recent activity is derived from eBay sold searches and separated into raw and graded records when the listing provides enough evidence. Public card pages summarize seven-day activity and recent observed sales. Longer windows are used to establish a baseline and to reduce the effect of a single busy day.
“Hot,” “warm,” and “quiet” are descriptive activity tiers, not buy or sell ratings. A card can trade frequently while falling in price, and a scarce card can be valuable despite few public sales. Search-result limits can also make a high-volume window incomplete; OPData labels truncated coverage where it can detect it.
Market index and movers
The OP TCG market index is the sum of the latest tracked raw prices across the supported catalog. Its history compares like snapshots over time. “Advancing” measures the share of tracked items moving upward, while the typical-card figure uses a median so premium chase cards do not dominate the result.
Gainers, losers, and set-screening tables are filters over recent snapshot changes. They are useful discovery tools, but thinly traded cards and recent catalog corrections can produce exaggerated percentages. Always open the underlying card page and examine the history and sales evidence before drawing a conclusion.
Pull-rate estimates
Bandai publishes card lists and product contents but generally does not publish English booster-box odds. OPData pull-rate tables therefore use documented case openings and community reports. Each set is labeled with a confidence level, source, and qualification. Provisional figures are updated as larger English samples become available.
These estimates describe observed collation patterns, not guarantees. Manga, signature, Treasure Rare, and other ultra-chase cards may occur at multi-case rarity. A sealed case or box should never be purchased on the assumption that a particular chase card is guaranteed.
Update cadence and corrections
Raw price synchronization runs daily. Sold-listing activity is collected daily, while graded-price, gem-rate, and release data follow their own scheduled jobs. Individual pages may update at different times because source availability, matching confidence, caching, and verification requirements differ.
Card-page reports are reviewed before data is hidden, overridden, or used to improve the matching rules. To report a problem, use the card-page report control or email errorreport@onepiecedata.com with the printing URL and supporting source.