Tag Genome Dataset Released

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Want to know how quirky a particular movie is? Or how to find the most visually appealing movies of all time? Or how to find a movie that is similar to another movie you’ve seen but less big budget and more cerebral?

The tag genome is a data structure that enables you to answer queries such as these. As described in this article, the tag genome encodes how strongly movies exhibit particular properties represented by tags (atmospheric, thought-provoking, realistic, etc.). The tag genome was computed using a machine learning algorithm on user-contributed content including tags, ratings, and textual reviews.

We’re announcing the release of a tag genome dataset, containing the relevance values for 1,128 tags and 9,734 movies. We hope you will explore this dataset and come up with new and creative ways to use it! You can find more details here.

Evaluating MOOC Learning — Experiences from our Recommender Systems Course

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Last fall Michael Ekstrand and I co-taught An Introduction to Recommender Systems on Coursera (if you search for the course, you can find the lectures open as part of the course preview).  In offering the course we had three goals:
  • to make a high-quality introductory recommender systems course available to the world
  • to actually experience the MOOC-teaching process, including exploring how elements of the MOOC could be useful in on-campus teaching
  • to study the effectiveness of the MOOC in student learning
To accomplish these goals, we had extensive support from not only videographers and course support staff, but also from learning technology and evaluation experts.  Our first published result of this work is the paper:
Teaching recommender systems at large scale:  Evaluation and lessons learned from a hybrid MOOC (Proceedings of the first ACM Conference on Learning @ Scalehttp://doi.acm.org/10.1145/2556325.2566244.

Social Curation in Pinterest: Specialization, Homophily, and Gender

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As the third-largest English-language social network behind Facebook and Twitter, Pinterest has surpassed Reddit, Digg, and others to become the world’s most popular social curation site. Despite the popularity of Pinterest, there has been little scientific work examining the strategies of successful Pinterest users. We have been studying Pinterest for the past year and a half, with one paper appearing in CHI 2013 and another one to be presented at CSCW 2014. This post summarizes the highlights of the CSCW paper.

In this work we studied the types of content and behavior that attract attention — namely repins and follows — in Pinterest. We looked at a number of factors, including the diversity of pinned content, homophily (the tendency for similar people to have more social connections), and gender.

Using our dataset of thousands of Pinterest users and millions of pins, we identified a number of factors that correlated with the number of followers a user had: the most powerful correlates were obvious factors like the amount of content the user pinned and the number of other users the user followed. However, topical diversity also played a role:  the more topically diverse one’s set of pins, the more followers one tends to have, but only up to a certain point. So, in other words, the Pinterest user who pins content in many categories – e.g. food/drink, DIY, home decor, travel, etc. – tends to have more followers than the Pinterest user who sticks to a single or small number of categories. However, when the diversity of categories gets too great, the number of followers tends to go down. The figure below shows this relationship in more detail.

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Deviant behavior in League of Legends: Do jerks drive off other players?

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This post describes work appearing at CSCW 2014.

Many online activities today involve interacting with other people, and these interactions are often dictated by social norms – unspoken rules that classify socially acceptable behavior.  Whether intentional or otherwise, people sometimes break these rules.  Behavior that goes against established norms is called deviant behavior, and in many cases is assumed to be negative. In online communities, deviant behavior is commonly believed to be harmful, and is expected to drive users to leave the community. For example, intentionally incorrect responses on a question and answer site may discourage new users from asking questions. Our work looks at patterns of player behavior in an online game where people will play bingo for money. We build a metric to predict a specific kind of deviant behavior, toxicity, and we use this metric to examine whether deviant behavior causes other players to quit.

We look at deviant behavior in the popular online game League of Legends.  League of Legends is a competitive multiplayer game where two teams of five players compete to destroy the other team’s base. Each player controls a single character, and every character has unique abilities which, when used skillfully, can help the player’s team overcome an enemy team. If you’ve never played League of Legends, check out this four-minute introduction video from League’s developer, Riot Games.

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GroupLens has gathered for a photograph

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Look at this group of nice folks! This GroupLens group photo was taken in the atrium of Keller Hall, where we work.

grouplens-2013

GroupLens, Fall 2013, back to front:

  • Jacob, Raghav, Zihong, Kate
  • Yilin, Brent, Morten
  • Pik-Mai, Steven, Dan
  • Zihong, Derian, Fernando
  • Vlad, Anu, Michael
  • Ting, Alison, Loren
  • Vikas, Max, Joe
  • Andrew, Daniel, Tien