elektronická verzia publikácie - FIIT STU - Slovenská technická ...

8
USER MODELING
FOR PERSONALIZED
WEB-BASED SYSTEMS
Michal Barla
It seems that the fact that the Web should be able to reflect and adapt to user needs is
commonly accepted nowadays. In order to do so, adaptive web-based systems need to have
some prior knowledge about its users. Acquisition of such knowledge is a task of user
modeling. User model can hold user characteristics related to user’s interests, knowledge,
background etc., according to actual used domain. However, it may take some time to
populate correctly the user model of a new user, so the system could provide meaningful
adaptation. This pose a risk, that user, unsatisfied by the system, leaves it and goes elsewhere
before it can prove its utility. Lack of information about a new user in adaptive systems is
called cold-start problem.
This chapter presents an overview of a domain of user modeling for web-based system,
with focus on sources for user modeling useful for cold-start problem solving. The first
section describes the basics of user modeling, introduces the modeling process and user
model representations, while second section describes various sources for user modeling
and discuss them from the cold-start problem point of view.
8.1 User Model Representations
Current adaptive web-based systems use mostly the following two types of user models [12]:
– stereotype model – is the simplest form of user model, which maps the individual user
onto one of (usually) predefined groups. All members of the same group would
experience the same “personalized” system. Even simpler form of stereotype model
is the scalar model [15]. It is usually used to capture the level of user domain knowledge
by a single value on a particular scale (e.g., good, average, none), usually set by the
user itself prior to using the system. Adaptation is then tailored to individual values
of the scale.
– overlay model – is currently the most popular user model representation, where the
model reflects user characteristics related to individual concepts of a domain model.
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