How our figures are calculated
What the figures and price pages on Wannonce count, how they are calculated and what they do not tell you.
The figures come only from the listings online on Wannonce at the time of the calculation. In a country where the site exists in several languages, every listing in the country counts, whatever its language: a price does not depend on the language of the listing.
The prices shown are asking prices, set by the sellers, not sale prices: the price actually paid may be lower, and we do not know it.
The price used is the one the listing shows at the time of the computation: for a negotiable listing, the asking price shown; for a listing whose price was lowered, the new price, not the original one. The price finally agreed between buyer and seller is not known.
The price shown is the median: half of the listings are cheaper, the other half more expensive. The price range runs from the lowest to the highest price once extreme prices have been excluded.
Before the calculation, a listing published several times by the same seller with the same title and the same price counts only once. Then extreme prices are excluded: any price more than one and a half times the interquartile range below the first quartile or above the third. The number of prices excluded is shown.
No figure without enough listings: a median needs at least 5 listings with a price. A city or region page is only offered to search engines once it has 20 listings, and a price page once it has 20 listings with a price.
Every median comes with a confidence level. High: at least 30 prices, and an interquartile range (the width of the middle half of the prices, from the first to the third quartile) of no more than 50% of the median. Medium: at least 10 prices, and an interquartile range of no more than 100% of the median. Low in every other case: few prices, or prices that are far apart because the category mixes different things.
Private sellers and professionals: a seller is a professional when their Pro account is active (“Pro” badge on their listings), a private seller otherwise. When each group has at least 5 prices, the page shows their median, range and number of prices side by side, each group cleaned on its own, and the gap between the two medians as a percentage of the private sellers' median. Otherwise a single figure covers all sellers.
Volume and turnover, over the last 30 days: new listings are those published for the first time over the period (a bumped listing keeps its first date). A listing ends when it is withdrawn (sold or not, the site does not know) or when it expires; the median time online is that of the listings that ended over the period, shown from 5 ended listings. The share still online covers the listings published in the 30 days before: those neither withdrawn nor expired 30 days after their publication, shown from 5 listings. Every category of the place, or the category and its sub-categories.
When a place has too few listings with a price in a category, the page shows the figures for the area that contains it (county, region or country) and says so on that line.
Once a week, a snapshot of the figures is saved. A change over time is only shown when there are at least two snapshots based on enough listings: the page then gives the median from a snapshot three to eight weeks old, with its date and its number of listings.
Updates: listing counts and prices are recalculated several times an hour; one snapshot is saved every week.
Limits: a median brings together items that differ in condition, age or model; with few listings it can change a lot from one week to the next. It does not replace a valuation.