Here's some relevant code snippets from SpecialRandomPage.php: $rand = mt_rand() / mt_getrandmax(); $randstr = number_format( $rand, 12, ".", "" ); $sqlget = "SELECT cur_id,cur_title FROM $cur $use_index WHERE cur_namespace=0 AND cur_is_redirect=0 $extra AND cur_random>$randstr ORDER BY cur_random LIMIT 1"; Here's the PHP documentation on mt_rand(): http://us2.php.net/mt_rand The salient points are: * A random number is generated using the PHP function mt_rand() * That number is used to find an article in the default namespace (not a redirect) with the closest greater cur_random value than the generated number. * The cur_random value is generated with mt_rand() and saved with the article in Article.php. It appears that if multiple articles should happen to share the same cur_random number, you could end up with a slight bias, since then the choice of which article to return is determined by how the database decides to order the articles, and if this isn't arbitrary then some articles are less likely to be returned than others. The degree of non-randomness that this implies probably depends on the number of articles and the range of the assignable random numbers. Hope this helps, Alan

On Sep 16, 2004, at 12:16 PM, samuel wrote: Depending on what you're trying to measure, simply taking a random selection of pages and looking at them in isolation may or may not be useful to you. Wikipedia is a permanent work in progress; its purpose is to generate content and grow and develop it over time. The actual distribution of a published or "stable" encyclopedia is a distinct project from the free-for-all editing on the wiki. Due to Wikipedia's nature it can be fully expected that many, many pages at any given time will be found wanting, because they are new or unpopular subjects and thus insufficiently developed. By the same token, Wikipedia can be fully expected to cover many topics that more traditional encyclopedias don't cover at all, or cover in less detail. If you're interested in comparing the quality of Wikipedia articles against that of more traditional encyclopedias, consider also doing random selection of topics covered by those encyclopedias, then seeking the same particular topics in Wikipedia for comparison. (And vice-versa!) Returnable pages are those in article namespace (not talk pages, user pages, etc) and not marked as redirects. From all articles that meet the above criteria, with one exception: on en.wikipedia.org the random selection has been hacked not to return pages last edited by the accounts Ram-Man or Rambot. This is a crude (and in my view unfortunate) hack to appease complaints that the random page function returned articles on cities and towns in the US too often. No. You are of course welcome to download the article database from http://download.wikimedia.org/ and select & sort articles in any fashion you see fit. -- brion vibber (brion @ pobox.com)