MATHEMATICAL STANDARDS

TokuPrice Sold-Price Index Methodology

TokuPrice operates on the principle that collectible toys deserve the same statistical discipline as financial equities. Below is our open methodology for secondary market transaction harvesting, outlier stripping, condition grading, and copyright compliance.

1. Why Medians Over Skewed Means

Secondary marketplace transaction data is inherently noisy. Single fraudulent sales, shill-bidding auctions, or unfulfilled best offers can wildly skew standard arithmetic means.

TokuPrice computes the 50th percentile median (P50) for all benchmark prices. If 15 copies of a DX Desire Driver sell between ¥7,500 and ¥8,800, and one rogue listing sells for ¥45,000, the median remains rock-solid at ¥8,200.

Median = Value at position (N + 1) / 2 in sorted transaction array

2. Automated Outlier Stripping (IQR Filtering)

Before any transaction enters a model's statistical pool, it passes through our automated classification and anomaly rejection pipeline:

  • Interquartile Range (IQR) Boundary: Any transaction falling outside [Q1 - 1.5 * IQR, Q3 + 1.5 * IQR] is flagged and quarantined.
  • Junk Lots & Bulk Bundles (まとめ売り): Multi-item bundle listings are programmatically identified and rejected using regex filters.
  • Miniature & Sub-variant Exclusions: Candy toys (Shokugan / SG), Gashapon (GP) capsules, mini-plastic models, and empty boxes are classified into separate categories and never contaminate DX/CSM model medians.
  • Card-Only & Paper Media Exclusions: Ride Chemy Cards, Kamen Rider Battle Ganbarizing / Ganbagiri cards, and flyer inserts sold separately are rejected.

3. Condition Grade Taxonomy

In Japanese toy collecting, condition accounts for 70%+ of transaction value. TokuPrice enforces 4 strict condition tiers:

New / Sealed (未開封)

Factory outer plastic intact or Bandai factory tape unpeeled. Zero box tampering.

Complete in Box (美品・完品)

Box opened, but item is complete with all instructions, cardboard inserts, belt straps, and accessories in near-mint condition.

Loose / Used (本体のみ・中古良品)

Toy body only without box. Minor normal display/play wear, electronics and sound effects 100% verified functional.

Parts & Scrap Floor (ジャンク)

Damaged electronics, broken hinges, missing battery covers, or heavy scratches. Reported as a scrap baseline only and excluded from functional medians.

4. Platforms Harvested

Liquidity for authentic Japanese tokusatsu toys is concentrated inside Japan. TokuPrice monitors completed sold transactions across:

Mercari Japan: Tokyo's largest consumer-to-consumer flea market platform.
Yahoo! Auctions Japan: Authoritative competitive bidding and rare vintage lot index.
Rakuma (Rakuten Flea Market): Fast-growing secondary Japanese mobile marketplace.
Mandarake Archive & Kaitori: The physical collector grading authority and domestic buyback cash floor.
Suruga-ya: Japanese domestic retailer bid-ask reference.

5. 100% Compliance & Zero Scraped Media Policy

TokuPrice respects intellectual property, platform terms, and privacy:

  • NO Scraped Seller Photos: We never host, cache, or display user photos from Japanese auctions or flea markets.
  • NO Scraped Descriptions: We never republish user listing text, seller commentary, or private transaction notes.
  • Aggregated Statistics Only: All published figures are mathematical derivatives (medians, percentiles, transaction counts, dates).