-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Martin Albisetti wrote on 09/04/15 13:38: > ... > > There are a lot of good points about people gaming the system and > problems with different approaches. Luckily, this is not a new > problem at all. In fact, it's not even new to Ubuntu! Matthew > Paul Thomas spent some time thinking about this years ago and put > together a great wiki page[1]. Which points to a great post on how > to avoid the most common problems: > http://www.evanmiller.org/how-not-to-sort-by-average-rating.html > > ...
The sorting algorithm we ended up with is described in the main USC specification. <https://wiki.ubuntu.com/SoftwareCenter#top-rated> "An item’s dampened rating (DR) should be 3 plus the sum, for each possible number of stars (1, 2, 3, 4, and 5), of (that number of stars – 3) multiplied by the lower bound of the Wilson score confidence interval with a 90% confidence level for the proportion of ratings that had that number of stars." This is similar to Selene's suggestion. It avoids messing with the displayed rating -- an item with only two reviews, both 5-star, will show an average rating of 5 stars, so people don't think the average is broken. But that item will sort below an item that has nine 5-star ratings and one 4-star rating, even though the raw average is higher. This is more understandable, because sorting can also be influenced by other factors as Martin mentioned -- popularity, usage, crashiness, serendipity, and so on. - -- mpt -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlUrlDkACgkQ6PUxNfU6ecoQRACeIRyrJFa+MvUD0DquPNJ4ptZq 8VkAnitPUgmTjvWO4KqOiC5mnQDGKVQN =Y8mV -----END PGP SIGNATURE----- -- Mailing list: https://launchpad.net/~ubuntu-phone Post to : [email protected] Unsubscribe : https://launchpad.net/~ubuntu-phone More help : https://help.launchpad.net/ListHelp
