Methodology and data basis

This page describes which price data OffersCheck has stored, how it comes about, and what can and cannot be concluded from it. Statements about price history on this website refer to this data basis.

What OffersCheck records

OffersCheck stores the offers and promotional prices of retailers as the retailers publish them themselves: weekly offers and online sale prices. A recorded offer is one stored price of a retailer for a product, with the day it was recorded and, where the retailer states it, the previous price.

The oldest stored entry of this website dates from 31 May 2015, the newest from 2 November 2026. In total, 583,544 offers from 18 retailers have been recorded.

How the data comes about

• The retailers' offers are retrieved automatically once a week.
• A price is stored when it is new: if an entry for the same retailer, the same product and the same price already exists from the last 120 days, no further entry is made.
• An entry therefore means: this price was new at this retrieval. An unchanged price does not create a new row, so the number of entries is not a number of offers per week.
• If the retrieval for a retailer fails, for example because its website changed, no entries are made for that time. Such gaps can occur, especially in the older years.

What the figures are not

• Not shelf prices: what is stored are promotional prices as retailers publish them in weekly offers or in their online shop, not the prices on the shelf.
• Not complete: not every retailer, not every product and not every week is included.
• Not the same in every year: which retailers were recorded has changed from year to year, see the table below.
• No proof of availability: a missing entry can mean an unchanged price, but also that the product was not offered or not retrieved.

The data basis in figures

The table shows for each calendar year how many offers were recorded, from how many retailers, and in how many calendar weeks at least one entry was made.

Retailers: retailers with at least one entry in the year. Weeks recorded: calendar weeks with at least one entry; a week that spans the new year counts in both years.

For 8,817 product pages there are entries from at least three different years, for 1,309 from at least five. This describes the length of the period, not whether it is covered without gaps.

Retailers with the longest continuous coverage

Continuous here means: there is at least one entry in every calendar year of the period. It does not mean that every week was recorded.

How to read a price history

• The price history shows the stored entries of a product in chronological order. Nothing was measured between two entries.
• “Lowest recorded price” is the lowest price among these entries. It is not necessarily the lowest price ever charged, because times without an entry and retailers that were not recorded are not included.
• If a price returns to an already stored value within 120 days, no new entry is made. A course from 5 to 6 and back to 5 can therefore appear as 5 to 6.

Data quality rules

• Prices of 0 or less are not shown.
• Individual recording errors at a multiple of the usual price are possible. Conspicuous cases are counted (see above) and corrected when reported.
• In the data, 6,569 entries have a price of 0 or less. For 78 product pages with at least 5 entries, the highest price is more than 20 times the lowest; these are signs of recording errors.

Corrections

Did you spot a wrong price or a gap? Write to us using the contact details in the Imprint. We look into reports of faulty data.

Figures as of: 4 November 2026. They are produced from the database by a script and not maintained by hand.