AI Valuation Methodology: Ask vs. Transacted Spread, IQR Outlier Filtering & Condition Multipliers
How ThaiAmuletExchange.com computes Recommended Buy and Recommended Sell bands across 108,284 market observations using Interquartile Range (IQR) filtering and condition/certificate adjustments.
1. Why Raw Averages Fail in Amulet Markets
Public auction and classified feeds contain two severe statistical distortions: ฿1–฿49 starting-bid placeholders and 9-to-10-digit Thai mobile phone numbers (081-xxx-xxxx / 09x-xxx-xxxx) typed into price fields by dealers.
ThaiAmuletExchange.com enforces a hard statistical boundary (฿50 to ฿10,000,000) and computes non-parametric percentiles (P15, P25, P50 Median, P75, P85) separately for Ask (LISTED) and Transacted (SOLD + AUCTION_HAMMER) pools.
2. Condition & Certification Multipliers
Once the baseline P50 Median is established for a series, the interactive Valuation Engine applies empirical multipliers for physical preservation (Competition Winner 1.45x, Unworn Mint 1.20x, Standard Circulated 1.00x, Worn/Repaired 0.60x) and authentication cards (Samakom Phra 1.25x, Thaprachan 1.20x, G-Pra/DD-Pra 1.10x, Uncertified Raw 0.80x).
3. Multi-Currency Equilibrium & Cross-Border Liquidity Arbitrage (THB / SGD / MYR / VND / USD)
| Factor / Tier | Multiplier | Market Rationale |
|---|---|---|
| Competition Winner (แชมป์งานประกวด) | 1.45x | Top-4 ribbon winner at a Samakom-sanctioned competition |
| Unworn Mint (ผิวเดิม จมูกโด่ง) | 1.20x | Original fire-skin / uncleaned crust with full high-relief nose |
| Standard Circulated (สภาพสวยใช้งาน) | 1.00x | Baseline market median specimen |
| Samakom Phra Smart Card | 1.25x | Eliminates counterparty authenticity risk for overseas buyers |
| Uncertified Raw (พระเปลือยไม่มีบัตร) | 0.80x | 20% risk & grading fee discount required by wholesale dealers |
