PLOTT DATA · marketplace demand estimation

We estimate demand on the marketplaces that never report it.

We collect public marketplace data and turn it into a demand estimate.

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Every number carries its confidence

Measured

Read as a real number from the marketplace.

Direct signal

Read from a strong proxy the marketplace shows.

Modeled

Inferred from review speed and supply.

None

Not available on this surface.

Coverage

Where we collect, and what we get.

Four capabilities per marketplace. The meter shows how sure each one is.

Marketplace

Categories

Supply & price

Demand

Sales history

TCGplayerTrading cards

Real units sold and price, weekly, back to 2021.

Categories

Measured

Supply & price

Measured

Demand

Measured

Sales history

Measured

WhatnotLive commerce

Seller sales rank for each category.

Categories

Measured

Supply & price

Direct signal

Demand

Direct signal

Sales history

Modeled

eBayGeneral resale

Sold listings across 1,454 categories.

Categories

Measured

Supply & price

Measured

Demand

Direct signal

Sales history

Modeled

WalmartGeneral marketplace

“100+ bought” demand badges by product.

Categories

Measured

Supply & price

Measured

Demand

Direct signal

Sales history

Modeled

PoshmarkResale fashion

Brand listing counts, likes, and offers.

Categories

Measured

Supply & price

Measured

Demand

Modeled

Sales history

Modeled

DiscogsMusic and media

19.5M releases with want and have counts.

Categories

Measured

Supply & price

Measured

Demand

Modeled

Sales history

Modeled

GOATSneakers

609k listings; price history by size.

Categories

Measured

Supply & price

Measured

Demand

Modeled

Sales history

Modeled

Back MarketRefurbished electronics

Price by grade across handset and laptop lines.

Categories

Measured

Supply & price

Measured

Demand

Modeled

Sales history

Modeled

MercariResale

3,190 categories and 25,110 brands.

Categories

Measured

Supply & price

Measured

Demand

Modeled

Sales history

Modeled

StockXSneakers, collectibles

Public catalog and ask prices.

Categories

Measured

Supply & price

Direct signal

Demand

Modeled

Sales history

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SHEINFast fashion

New-arrival and price speed.

Categories

Direct signal

Supply & price

Modeled

Demand

Modeled

Sales history

—

11 marketplaces tested live · 1 with measured sales · the rest are direct signals or models, each labeled

What we provide

What we read, and what we model.

One side is a fact. The other is a model. We never mix them.

Read directly

Measured

Read straight from the marketplace.

Category structureThe full category tree, with IDs.
Listings and supplyThe count of products and sellers per category.
Price and discountThe listed price and any markdown.
Reviews and ratingThe review count and the star rating per product.
Seller sold countsLifetime units, where the seller page shows them.
Demand badgesBands such as “100+ bought”, where the marketplace shows them.
Real units soldDaily and weekly sales, on marketplaces that publish them.

Modeled

Each one comes from a named method.

Units sold per periodNew reviews ÷ review rate. The rate is 2 to 4 percent.
Category sale valueUnits × price, or supply × average order value.
Growth rateThe change between snapshots over four weeks or more.
Sell-throughEstimated units ÷ active supply.
Market rank by demandProducts ordered by estimated units for each category.

Method

How we estimate demand.

Where a marketplace hides sales, review speed stands in for it.

01
Record
We take a snapshot each day. We keep review counts, ranks, and prices for every product.
02
Link
A review count rises when people buy. The rise tracks the number of sales.
03
Estimate
We divide new reviews by a review rate of 2 to 4 percent to estimate units.
04
Calibrate
We fit the rate to one quarter of your own sales. The estimate becomes a model.

estimated units = new reviews ÷ review rate

review rate is 2 to 4 percent, then calibrated to client sales

Confidence over time

A guide on day one. Reliable by week four.