Population Model

A population of people is comprised of “meta-groups.” Within a meta-group, all parameters such as hospitalization rate remain constant with the exception of contact level. For example, in modeling a university, possible meta-groups could be undergraduates, graduates, professional students, and faculty/staff. A meta-group contact matrix encodes how often these meta-groups come into contact with one another. Within each meta-group, there are multiple groups that represent varying contact levels.

The simpar.groups.MetaGroup class allows one to specify a vector of number of contacts across meta-groups as well as a vector indicating what fraction of the meta-group population is in each of these groups. Alternatively, this can be specified with a truncated Pareto distribution. Given a shape parameter \alpha and truncation point ub, the fraction of the meta-group population with i contacts is f(i;\alpha,ub) where f is the probability density function of the Pareto distribution. Note these values are normalized to sum to 1.

The interactions among individuals within the same meta-group is assumed to be well-mixed in that the amount of interaction group i has with group j is proportional to both groups contact levels and the fraction of the population of group j. Hence, it is not assumed that more social people tend to interact with more social people and vice versa. Similarly, while the meta-group contact matrix encodes how much contact takes place between two meta-groups, the interaction between them is assumed to be well-mixed with respect to the groups that comprise them. See simpar.groups.MetaGroup and simpar.groups.Population for more details.