sim.pointSource {surveillance}R Documentation

Generation of Simulated Point Source Epidemy

Description

Simulation of epidemies which were introduced by point sources. The basis of this proagramme is a combination of a Hidden Markov Modell (to get random timepoints for outbreaks) and a simple model (compare sim.seasonalNoise) to simulate the epidemy.

Usage

    sim.pointSource(p = 0.99, r = 0.01, length = 400, A = 1, 
        alpha = 1, beta = 0, phi = 0, frequency = 1, state = NULL, K)

Arguments

p probability to get a new epidemy at time i if there was one at time i-1, default 0.99.
r probability to get no new epidemy at time i if there was none at time i-1, default 0.01.
length number of weeks to model, default 400. length is ignored if state is given. In this case the length of state is used.
A amplitude (range of sinus), default = 1.
alpha parameter to move along the y-axis (negative values not allowed) with alpha > = A, default = 1.
beta regression coefficient, default = 0.
phi factor to create seasonal moves (moves the curve along the x-axis), default = 0.
frequency factor to determine the oscillation-frequency, default = 1.
state use a state chain to define the status at this timepoint (outbreak or not). If not given a Markov chain is generated by the programme, default NULL.
K additional weigth for an outbreak which influences the distribution parameter mu, default = 0.

Value

disProg a object disProg (disease progress) including a list of the observed, the state chain and nearly all input parameters.

Author(s)

M. Höhle, A. Riebler, C. Lang

See Also

sim.seasonalNoise

Examples

    # Plotting of simulated data
    disProgObj <- sim.pointSource(p = 0.99, r = 0.5, length = 208,
                                    A = 1, alpha = 1, beta = 0, phi = 0,
                                    frequency = 1, state = NULL, K = 2)
    # plot the simulated disease with the defined outbreaks
    plot(disProgObj)

    state <- rep(c(0,0,0,0,0,0,0,0,1,1), 20)
    disProgObj <- sim.pointSource(state = state, K = 1.2)
    plot(disProgObj)

[Package surveillance version 1.0-3 Index]