ABSTRACT
We have so far reviewed the most frequently used models for describing both the individual parameters (ψi) and the observations (yi), but several extensions can be considered.
For instance, if we assume that a population consists of several homogeneous subpopulations, mixture models can be very useful for describing different types of mixtures such as mixtures of distributions, mixtures of structural models and mixtures of residual models (see Section 6.1).
