DES models
DES models represent a mathematic modelling method. In these models events are simulated in a continuous manner. As opposed to Markov models, in DES models no cycles of a specific length are modelled and no states with probabilities of transition between them are defined. These are replaced with "events", for which the time of occurrence and/or parameters are randomly assigned (e.g. if the loss of body weight is modelled as an event, the time of weight loss and the number of lost kilograms will be assigned randomly). As the time is modelled in a continuous and not discrete manner, events may occur at any time and not only at specific moments of the cycle, like in Markov models. Each event may affect the patient's characteristics and vice versa ? the time at which a specific event will occur may depend on the patient's characteristics. In addition, the patient's characteristics, such as age or the degree of disability, may continuously change with time.