In their study they focus on the issue of modeling user characteristics rather than the issue of investigating the mental models of the users. Exploited user stereotypes 2. Poorly organized stereotypes 3. Poor user classification 4. They also use a different classification system for stereotypes that we will get into later.
Classes also overlap so that users can fit into more than one class.
They describe a model as an abstraction of reality that lets you focus on relevant characteristics. So a user model is one that represents characterstics of a user that are relevant to the goal of supporting an effective and graceful man-machine interaction. In other words, the user has to do less, the user likes it, and the user likes his bill at the end. The dialog manager which works between the user and the interface, a support problem solver which simulates the user and works with the target system and the user modeler which doesn't have a direct link with either the user OR the target system, but manages the user models. The purpose of the user modeling system is to gather information about the user, either single items or clusters of items - both linguistic or conceptual.