Abstract
Historical user activity is key for building user proles to
predict the user behavior and anities in many web ap-
plications such as targeting of online advertising, content
personalization and social recommendations. User proles
are temporal, and changes in a user's activity patterns are
particularly useful for improved prediction and recommen-
dation. For instance, an increased interest in car-related web
pages may well suggest that the user might be shopping for
a new vehicle.In this paper we present a comprehensive sta-
tistical framework for user proling based on topic models
which is able to capture such eects in a fully unsupervised
fashion. Our method models topical interests of a user dy-
namically where both the user association with the topics
and the topics themselves are allowed to vary over time,
thus ensuring that the proles remain current.
We describe a streaming, distributed inference algorithm
which is able to handle tens of millions of users. Our re-
sults show that our model contributes towards improved
behavioral targeting of display advertising relative to base-
line models that do not incorporate topical and/or tempo-
ral dependencies. As a side-eect our model yields human-
understandable results which can be used in an intuitive
fashion by advertisers.