Population dynamics

The following parameters determine characteristics related to population dynamics, such as age distribution, births, deaths, and gender. The values set here generally interact closely with values in the demographics file.

Note

Parameters are case-sensitive. For Boolean parameters, set to 1 for true or 0 for false. Minimum, maximum, or default values of “NA” indicate that those values are not applicable for that parameter.

EMOD does not use true defaults; that is, if the dependency relationships indicate that a parameter is required, you must supply a value for it. However, many of the tools used to work with EMOD will use the default values provided below.

JSON format does not permit comments, but you can add “dummy” parameters to add contextual information to your files. Any keys that are not EMOD parameter names will be ignored by the model.

Parameter

Data type

Minimum

Maximum

Default

Description

Example

Age_Initialization_Distribution_Type

enum

NA

NA

DISTRIBUTION_OFF

The method for initializing the age distribution in the simulated population. Possible values are:

DISTRIBUTION_OFF

All individuals default to age 20 years old.

DISTRIBUTION_SIMPLE

Individual ages are drawn from a distribution whose functional form is specified in the demographics file using the IndividualAttributes simple Age distribution parameters.

DISTRIBUTION_COMPLEX

Individual ages are drawn from a piecewise linear function specified in the demographics file complex distribution parameters.

{
    "Age_Initialization_Distribution_Type": "DISTRIBUTION_SIMPLE"
}

Default_Geography_Initial_Node_Population

integer

0

1000000

1000

When using the built-in demographics for default geography, the initial number of individuals in each node. Note that the built-in demographics feature does not represent a real geographical location and is mostly used for testing. Enable_Demographics_Builtin must be set to true (1).

{
    "Enable_Demographics_Builtin": 1,
    "Default_Geography_Initial_Node_Population": 1000,
    "Default_Geography_Torus_Size": 3
}

Demographics_Filenames

array of strings

NA

NA

An array of the paths to demographics files containing information on the identity and demographics of the region to simulate. The files must be in .json format. Note that this parameter is only required when Enable_Demographics_Builtin is set to 0.

{
    "Demographics_Filenames": [
        "Namawala_single_node_demographics.json",
        "Namawala_demographics_overlay.json"
    ]
}

Enable_Aging

boolean

0

1

1

Controls whether or not individuals in a population age during the simulation. Enable_Vital_Dynamics must be set to true (1).

{
    "Enable_Vital_Dynamics": 1,
    "Enable_Aging": 1
}

Enable_Birth

boolean

0

1

1

Controls whether or not individuals will be added to the simulation by birth. Enable_Vital_Dynamics must be set to true (1). If you want new individuals to have the same intervention coverage as existing individuals, you must add a BirthTriggeredIV to the campaign file.

{
    "Enable_Vital_Dynamics": 1,
    "Enable_Birth": 1
}

Enable_Demographics_Birth

boolean

0

1

0

Controls whether or not newborns have disease risk drawn from a distribution; uniform disease risk if false. Enable_Birth, Enable_Demographics_Risk, and Enable_Vital_Dynamics must be set to true (1).

{
    "Enable_Birth": 1,
    "Enable_Demographics_Birth": 1,
    "Enable_Vital_Dynamics": 1
}

Enable_Demographics_Builtin

boolean

0

1

0

Controls whether or not built-in demographics for default geography will be used. Note that the built-in demographics feature does not represent a real geographical location and is mostly used for testing. Set to true (1) to define the initial population and number of nodes using Default_Geography_Initial_Node_Population and Default_Geography_Torus_Size. Set to false (0) to use demographics input files defined in Demographics_Filenames.

{
    "Enable_Demographics_Builtin": 1,
    "Default_Geography_Initial_Node_Population": 1000,
    "Default_Geography_Torus_Size": 3
}

Enable_Vital_Dynamics

boolean

0

1

1

Controls whether or not births and deaths occur in the simulation. Births and deaths must be individually enabled and set.

{
    "Enable_Vital_Dynamics": 1,
    "Enable_Birth": 1,
    "Death_Rate_Dependence": "NOT_INITIALIZED",
    "Base_Mortality": 0.002
}

Minimum_Adult_Age_Years

float

0

3.40E+38

15

The age, in years, after which an individual is considered an adult. Individual_Sampling_Type must be set to ADAPTED_SAMPLING_BY_AGE_GROUP.

{
    "Minimum_Adult_Age_Years": 17
}

Population_Density_Infectivity_Correction

enum

NA

NA

CONSTANT_INFECTIVITY

Correction to alter infectivity by population density set in the Population_Density_C50 parameter. Measured in people per square kilometer. Possible values are:

  • CONSTANT_INFECTIVITY

  • SATURATING_FUNCTION_OF_DENSITY

Note

Sparsely populated areas have a lower infectivity, while densely populated areas have a higher infectivity, which rises to saturate at the Base_Infectivity value.

{
    "Population_Density_Infectivity_Correction": "SATURATING_FUNCTION_OF_DENSITY"
}

Population_Scale_Type

enum

NA

NA

USE_INPUT_FILE

The method to use for scaling the initial population specified in the demographics input file. Possible values are:

USE_INPUT_FILE

Turns off population scaling and uses InitialPopulation in the demographics file (see NodeAttributes parameters).

FIXED_SCALING

Enables Base_Population_Scale_Factor.

{
    "Population_Scale_Type": "FIXED_SCALING"
}

x_Base_Population

float

0

3.40E+38

1

Scale factor for InitialPopulation in the demographics file (see NodeAttributes parameters). If Population_Scale_Type is set to FIXED_SCALING, the initial simulation population is uniformly scaled over the entire area to adjust for historical or future population density.

{
    "x_Base_Population": 0.0001
}

x_Birth

float

0

3.40E+38

1

Scale factor for birth rate, as provided by the demographics file (see NodeAttributes parameters). Enable_Birth must be set to 1.

{
    "x_Birth": 1
}