# Scalars and multipliers¶

The following parameters scale or multiply values set in other areas of the configuration file or other input files. This can be especially useful for understanding the sensitivities of disease dynamics to input data without requiring modifications to those base values. For example, one might set x_Birth to a value less than 1 to simulate a lower future birth rate due to increased economic prosperity and available medical technology.

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

Birth_Rate_Time_Dependence

enum

NA

NA

NONE

A scale factor for BirthRate that allows it to be altered by time or season. Enable_Birth must be set to true (1). Possible values are:

NONE

Birth rate does not vary by time.

SINUSOIDAL_FUNCTION_OF_TIME

Allows birth rate to be time-dependent, following a sinusoidal shape defined by $$1 + \sin \text{Birth\_Rate\_Sinusoidal\_Forcing\_Amplitude} \times \sin(2 \pi \times (\text{day} - \sin \text{Birth\_Rate\_Sinusoidal\_Forcing\_Phase})/365)$$. Set Birth_Rate_Sinusoidal_Forcing_Amplitude and Birth_Rate_Sinusoidal_Forcing_Phase.

ANNUAL_BOXCAR_FUNCTION

Allows birth rate to follow a boxcar function. The scale factor will be equal to 1 except for a single interval in which it is equal to a given constant equal to 1 + Birth_Rate_Boxcar_Forcing_Amplitude. Set Birth_Rate_Boxcar_Forcing_Amplitude, Birth_Rate_Boxcar_Forcing_End_Time, and Birth_Rate_Boxcar_Forcing_Start_Time.

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


Infectivity_Exponential_Baseline

float

0

1

0

The scale factor applied to Base_Infectivity at the beginning of a simulation, before the infectivity begins to grow exponentially. Infectivity_Scale_Type must be set to EXPONENTIAL_FUNCTION_OF_TIME.

{
"Infectivity_Exponential_Baseline": 0.1,
"Infectivity_Exponential_Delay": 90,
"Infectivity_Exponential_Rate": 45,
"Infectivity_Scale_Type": "EXPONENTIAL_FUNCTION_OF_TIME"
}


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"
}


Post_Infection_Acquisition_Multiplier

float

0

1

0

The multiplicative reduction in the probability of reacquiring disease. At the time of recovery, the immunity against acquisition is multiplied by Acquisition_Blocking_Immunity_Decay_Rate x (1 - Post_Infection_Acquisition_Multiplier). Enable_Immunity must be set to 1 (true).

{
"Enable_Immunity": 1,
"Enable_Immune_Decay": 1,
"Post_Infection_Acquisition_Multiplier": 0.9
}


Post_Infection_Mortality_Multiplier

float

0

1

0

The multiplicative reduction in the probability of dying from infection after getting reinfected. At the time of recovery, the immunity against mortality is multiplied by Mortality_Blocking_Immunity_Decay_Rate x (1 - Post_Infection_Mortality_Multiplier). Enable_Immunity must be set to 1 (true).

{
"Enable_Immunity": 1,
"Enable_Immune_Decay": 1,
"Post_Infection_Mortality_Multiplier": 0.5
}


Post_Infection_Transmission_Multiplier

float

0

1

0

The multiplicative reduction in the probability of transmitting infection after getting reinfected. At the time of recovery, the immunity against transmission is multiplied by Transmission_Blocking_Immunity_Decay_Rate x (1 - Post_Infection_Transmission_Multiplier). Enable_Immunity must be set to 1 (true).

{
"Enable_Immunity": 1,
"Enable_Immunity_Decay": 1,
"Post_Infection_Transmission_Multiplier": 0.9
}


x_Air_Migration

float

0

3.40E+38

1

Scale factor for the rate of migration by air, as provided by the migration file. Enable_Air_Migration must be set to 1.

{
"Scale_Factor_Air_Migration": 1
}


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
}


x_Family_Migration

float

0

3.40E+38

1

Scale factor for the rate of migration by families, as provided by the migration file. Enable_Family_Migration must be set to true (1).

{
"x_Family_Migration": 1
}


x_Local_Migration

float

0

3.40E+38

1

Scale factor for rate of migration by foot travel, as provided by the migration file. Enable_Local_Migration must be set to 1.

{
"x_Local_Migration": 1
}


x_Other_Mortality

float

0

3.40E+38

1

Scale factor for mortality from causes other than the disease being simulated. Base mortality is provided by the demographics file (see Complex distributions parameters). Enable_Natural_Mortality must be set to 1.

{
"x_Other_Mortality": 1
}


x_Regional_Migration

float

0

3.40E+38

1

Scale factor for the rate of migration by road vehicle, as provided by the migration file. Enable_Regional_Migration must be set to 1.

{
"x_Regional_Migration": 1
}


x_Sea_Migration

float

0

3.40E+38

1

Scale factor for the rate of migration by sea, as provided by the migration file. Enable_Sea_Migration must be set to 1.

{
"x_Sea_Migration": 1
}