Items by Dasdan, Ali

Human computation is an effective way to channel human effort spent playing games to solving computational problems that are easy for humans but difficult for computers to automate. We propose Thumbs-Up, a new game for human computation with the purpose of playing to rank search result. Our experience from users shows that Thumbs-Up is not only fun to play, but produces more relevant rankings than both a major search engine and optimal rank aggregation using the Kemeny rule.

In order to return relevant search results, a search engine must keep its local repository synchronized to the Web, but it is usually impossible to attain perfect freshness. Hence, it is vital for a production search engine continually to monitor and improve repository freshness. Most previous freshness metrics, formulated in the context of developing better synchronization policies, focused on the web crawler while ignoring other parts of a search engine. But, the freshness of documents in a web crawler does not necessarily translate directly into the freshness of search results as seen by users. We propose metrics for measuring freshness from a user’s perspective, which take into account the latency between when documents are crawled and when they are viewed by users, as well as the variation in user click and view frequency among different documents. We also describe a practical implementation of these metrics that were used in a production search engine.

Social bookmarking has emerged as a growing source of human generated content on the web. In essence, bookmarking involves URLs and tags on them. In this paper, we perform a large scale study of the usefulness of bookmarked URLs from the top social bookmarking site Delicious. Instead of focusing on the dimension of tags, which has been covered in the previous work, we explore social bookmarking from the dimension of URLs. More specifically, we investigate the Delicious URLs and their content to quantify their value to a search engine. For their value in leading to good content, we show that the Delicious URLs have higher quality content and more external outlinks. For their value in satisfying users, we show that the Delicious URLs have more clicked URLs as well as get more clicks. We suggest that based on their value, the Delicious URLs should be used as another source of seed URLs for crawlers.