Description Usage Arguments Details Act Balancing New Modules See Also
Sets the epidemic parameters for stochastic individual contact
models simulated with icm
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 
inf.prob 
Probability of infection per transmissible act between a susceptible and an infected person. In twogroup models, this is the probability of infection for the group 1 members. 
inter.eff 
Efficacy of an intervention which affects the peract probability of infection. Efficacy is defined as 1  the relative hazard of infection given exposure to the intervention, compared to no exposure. 
inter.start 
Time step at which the intervention starts, between 1 and
the number of time steps specified in the model. This will default to
1 if the 
act.rate 
Average number of transmissible acts per person per unit
time. For twogroup models, this is the number of acts per group 1
persons per unit time; a balance between the acts in groups 1 and 2 is
necessary, and set using the 
rec.rate 
Average rate of recovery with immunity (in 
a.rate 
Arrival or entry rate. For onegroup models, the arrival rate
is the rate of new arrivals per person per unit time. For twogroup
models, the arrival rate may be parameterized as a rate per group 1
person time (with group 1 persons representing females), and with the

ds.rate 
Departure or exit rate for susceptible. For twogroup models, it is the rate for the group 1 susceptible only. 
di.rate 
Departure or exit rate for infected. For twogroup models, it is the rate for the group 1 infected only. 
dr.rate 
Departure or exit rate for recovered. For twogroup models,
it is the rate for the group 1 recovered only. This parameter is only
used for 
inf.prob.g2 
Probability of infection per transmissible act between a susceptible group 2 person and an infected group 1 person. It is the probability of infection to group 2 members. 
act.rate.g2 
Average number of transmissible acts per group 2 person
per unit time; a balance between the acts in groups 1 and 2 is
necessary, and set using the 
rec.rate.g2 
Average rate of recovery with immunity (in 
a.rate.g2 
Arrival or entry rate for group 2. This may either be
specified numerically as the rate of new arrivals per group 2 persons
per unit time, or as 
ds.rate.g2 
Departure or exit rate for group 2 susceptible. 
di.rate.g2 
Departure or exit rate for group 2 infected. 
dr.rate.g2 
Departure or exit rate for group 2 recovered. This
parameter is only used for 
balance 
For twogroup models, balance the 
... 
Additional arguments passed to model. 
param.icm
sets the epidemic parameters for the stochastic individual
contact models simulated with the icm
function. Models
may use the base types, for which these parameters are used, or new process
modules which may use these parameters (but not necessarily). A detailed
description of ICM parameterization for base models is found in the
Basic ICMs tutorial.
For base models, the model specification will be chosen as a result of
the model parameters entered here and the control settings in
control.icm
. Onegroup and twogroup models are available,
where the former assumes a homogeneous mixing in the population and the
latter assumes a purely heterogeneous mixing between two distinct partitions
in the population (e.g., men and women). Specifying any group two parameters
(those with a .g2
) implies the simulation of a twogroup model. All
the parameters for a desired model type must be specified, even if they are
zero.
In twogroup models, a balance between the number of acts for group 1 members
and those for group 2 members must be maintained. With purely heterogeneous
mixing, the product of one group size and act rate must equal the product of
the other group size and act rate: N_1 α_1 = N_2 α_2, where
N_i is the group size and α_i the groupspecific act rates
at time t. The balance
parameter here specifies which group's
act rate should control the others with respect to balancing. See the
Basic DCMs tutorial.
To build original models outside of the base models, new process modules
may be constructed to replace the existing modules or to supplement the
existing set. These are passed into the control settings in
control.icm
. New modules may use either the existing model
parameters named here, an original set of parameters, or a combination of
both. The ...
allows the user to pass an arbitrary set of original
model parameters into param.icm
. Whereas there are strict checks with
default modules for parameter validity, these checks are the user's
responsibility with new modules.
Use init.icm
to specify the initial conditions and
control.icm
to specify the control settings. Run the
parameterized model with icm
.
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