24.5.1.2 Model-based approaches
Model-based approaches construct a predictive model to estimate unknown ratings
by learning from the observed data. Several existing approaches for multi-criteria
rating recommenders fall into this category, including aggregation function, probabilistic modeling, and multilinear singular value decomposition (MSVD).
Aggregation function approach. While overall rating r0 is often considered sim-
ply as just another criterion rating in similarity-based heuristic approaches (as illustrated earlier), the aggregation function approach assumes that the overall rating
serves as an aggregate of multi-criteria ratings [2]. Given this assumption, this approach finds aggregation function f that represents the relationship between overall
and multi-criteria ratings, i.e.,