In item tooltips, why does Auctionator display the most recently scanned price rather than an average of some sort - TheMouseNest/Auctionator GitHub Wiki

Of course, what we all want is a good estimate of how much a particular item will sell for at the auction house. The question then is whether there is a mathematical function - be it simple historical averaging or something more sophisticated - that can yield a better estimate than simply showing the most recently scanned low price.

It's certainly possible that there is, but I would bet that it would require quite a bit of sophisticated data analysis and would yield a only a marginal improvement. Doing something simple, like averaging prices over time or averaging all auctions of the AH is almost certainly going to be worse, in general, then just showing the current low price.

After the 4.0.1 patch came out, glyph prices on my server jumped up to around 75g and were selling briskly at that rate. But every once in a while one player would post a bunch at a very specific price around 25g. I'm guessing that some auction house mod was recommending that price based on some average that included prices before the patch. That's a problem with using historic data - things change in WoW. Even when they change less abruptly, averages will respond slowly to upward and downward trends.

The other reason Auctionator displays the most recent price, is that it's very clear what it is. It isn't some estimate based on historic data of unknown duration, weighted according to some unknown scheme, minus outliers of unknown definition. Is the most recent price always going to be a good estimate of what an item will sell for? Not always. But that's also the case for the result of more complicated averages. If you look in the comments or on the forums for other auction house addons, you'll find plenty of questions about wacky price estimates.