Table 3.

Procedure of dynamic model creation and simulation.

Step	Comment
Identification of variables	Expert consensus based on a set of prominent routinely assessed clinical variables
	The variable can be scalar (single value) or vector (multiple values) type. Example of scalar is patient's age, example of vector is “Other somatic pathologies”
Construction of causal-loop diagram (CLD)	Based on the assumed existence of a relationship between variables that is either scientifically validated and documented (e.g., depression and quality of nighttime sleep) or self-evident (expected specific effect of stimulants on sleepiness), or based on systems analysis and expert consensus.
	“Causal” in models of complex non-linear systems does not refer to causality in a common meaning of the word.
Construction of stock and flow diagram	Step-by-step process based on the system-dynamic methodology, mathematization of variables, relations and their notation in the form of a system of differential equations.
Setting of delays	The impact of changes is delayed in dynamic systems, the length and type of delay is set according to the input data received.
Normalization of input data	Input data were acquired in various units, to be comparable they must be converted to a common scale.
Setting of initial values	The normalized data are inserted into a system of differential equations and the model becomes simulation-ready.
Simulation	The output of the simulation is obtained by solving a system of differential equations in a given sequence of steps representing the time from the onset of the disease to the time of the interview.