24.5.1 Engaging Multi-Criteria Ratings during Prediction
This section provides an overview of the techniques that use multi-criteria ratings to
predict an overall rating or individual criteria ratings (or both). In general, recommendation techniques can be classified by the formation of the utility function into
two categories: heuristic-based (sometimes also referred to as memory-based) and
model-based techniques [4]. Heuristic-based techniques compute the utility of each
item for a user on the fly based on the observed data of the user and are typically
based on a certain heuristic assumption. For example, a neighborhood-based tech-
nique – one of the most popular heuristic-based collaborative filtering techniques
– assumes that two users who show similar preferences on the observed items will
have similar preferences for the unobserved items as well. In contrast, model-based
techniques learn a predictive model, typically using statistical or machine-learning
methods, that can best explain the observed data, and then use the learned model
to estimate the utility of unknown items for recommendations. Following this classification, we also present the algorithms of multi-criteria rating recommenders by
grouping them into heuristic and model-based approaches.