Onboarding New Users in Recommender Systems

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According to the song, “Getting to know you…. getting to know all about you…” is a lot of fun. But when you go to a new doctor, and fill out a 10-page patient intake form so the doctor can get to know you, it’s not so much fun.

The same has been true for recommender systems. A typical experience for new users is to rate a bunch of items to let the system know their preferences. For example, in the MovieLens film recommender, first-time visitors had to rate 15 movies (see the screen below). This process usually required paging through multiple screens, took over 5 minutes, and discouraged some people so much they dropped out before ever making it to the site home page! (more…)

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.