Overriding a model
Patients from an in silico clinical trial share the same computational model (CM). They differ from each other through CM overrides, i.e. modifications of some CM constructs.
What can be overriden in a model
Constructs that can be overriden in a CM are:
parameters: the value of any parameter can be overriden
variables: the initial condition of any variable can be overriden
compartments: the volume of any compartment can be overriden
What can be used to override a model
The above can be overriden with either:
A [Protocol] can override a CM construct with either a plain numerical value or with a formula (i.e. can depend on the values of other constructs)
Virtual Population overrides
Virtual Population overrides correspond to the values taken by patient-specific descriptors. Contrary to a
Virtual Population can only override CM constructs with numerical values
Order of precedence
In case of conflicts,
Protocol overrides always take precedence over
Virtual Population overrides:
- If no protocol or Virtual Population overrides a construct, the value it takes is the one defined in the CM.
- If a
Virtual Populationoverrides a construct, it will vary across the population, meaning each patient will be assigned with a different value
- If a
Protocoloverrides a construct, the protocol override takes precedence over any existing
Virtual Populationoverride. Therefore the construct will be take a different value for each protocol arm but will be constant across the population in a given arm.