Methodology

wocharts.de shows how prices of entire product markets develop – just as a stock index summarises the performance of a market. Every product with an EAN is its own ticker with a price chart.

Data sources

The basis is the offers that the 15 specialist portals of the wo● family retrieve several times a day from eBay, MediaMarkt and other German shops. For each offer and day the lowest price is stored (new goods, incl. VAT, excl. shipping). Days are counted in German time (Europe/Berlin).

Not included: Amazon. Under the Amazon Associates terms, Amazon prices are not part of price histories, indices, price movements or price alerts. The portals only show them as the current price – at most 24 hours old and with the time of retrieval. eBay offers are also shown with the time they were retrieved.

Which constituents count

A market index contains the portal's main products: new goods only, no accessories and no spare parts, duplicate offers of the same model merged, obvious misassignments (below 10% of the median price) removed. Only offers from commercial sellers count: eBay listings are included only if eBay reports a business seller account – private sales and sellers whose account type is not yet known are excluded. Category indices use the same selection rules as the portals' comparison pages and are created from eight constituents.

Calculation

• Chaining: For each day the price ratio today/yesterday is formed for every constituent that has a price on both days. New or disappearing products therefore do not distort the index.
• Average: Geometric mean of the ratios (Jevons index) – robust against individual outliers and without the upward bias of a simple average.
• Outliers: Daily changes above +50% or below −33% are treated as data errors (variant, accessory) and do not count. Short gaps of up to three days are bridged with the last price.
• Minimum size: If a day has fewer than five comparable pairs, the index remains unchanged.
• Base: 100 on 06/07/2026, the start of recording; markets that start later begin at 100 on their first day.
• Permanent record: Stored days are normally not changed retrospectively; only the last three days are recalculated. Exception: when a selection rule is corrected, all series are recalculated once from the start – last time on 18 October 2026 (exclusion of private sellers).

Sectors and wo* Price Index

Sector indices and the wo* Price Index chain the geometric mean of the daily factors of their markets – each market counts equally, regardless of the number of its products.

• Energy & Home: Solar system Index, Battery storage Index, Energy meter Index
• Home & Garden: Air conditioner Index, Grill Index, Pool Index
• Mobility: E-bike Index, E-scooter Index
• Tech & Gadgets: Smartphone Index, Laptop Index, Tablet Index, Games console Index
• Hobby & Lifestyle: Sneaker Index, Watch Index
• Health: Vitamin supplement Index

Biggest movers

The movers lists compare an offer's current price with the lowest price of the same product (same EAN, otherwise same brand and model) 1, 7 or 30 days earlier. A movement is only listed if it is confirmed:

• the new price level has held for at least two days (7 and 30 days; within 5%),
• the product has an EAN ticker, or at least two offers of the same model are at the new price level (within 10%),
• without an EAN, changes of more than ±35% are not shown; with an EAN the limit is ±50%.

EAN tickers

A ticker's chart shows the daily best price across all new-goods offers with this EAN – even if the product is listed on several portals or at several shops. In the comparison all curves are normalised to 100 on the first day of the selected period. Dedicated pages for search engines only exist for tickers with at least 30 days of history or several sources.

Colours and limitations

Green means falling prices (good for buyers), red rising ones. Product prices do not follow stock market rules: indicators such as moving averages or RSI are for orientation only. All information without guarantee; no purchase or investment advice.

Data as JSON

Every index series is freely available, e.g. /api/v1/index/wo or /api/v1/index/markt:ebike.