simdata_cont | R Documentation |
Multi-dimensional simulation function for continuous-time SPM.
simdata_cont( N = 10, a = -0.05, f1 = 80, Q = 2e-08, f = 80, b = 5, mu0 = 1e-05, theta = 0.08, ystart = 80, tstart = 30, tend = 105, dt = 1, sd0 = 1, nobs = NULL, gomp = TRUE, format = "long" )
N |
Number of individuals. |
a |
A k by k matrix, represents the adaptive capacity of the organism |
f1 |
A trajectory that corresponds to the long-term average value of the stochastic process Y(t), which describes a trajectory of individual covariate (physiological variable) influenced by different factors represented by a random Wiener process W(t). This is a vector with length of k. |
Q |
A matrix k by k, which is a non-negative-definite symmetric matrix, represents a sensitivity of risk function to deviation from the norm. |
f |
A vector with length of k, represents the normal (or optimal) state of physiological variable. |
b |
A diffusion coefficient, k by k matrix, characterizes a strength of the random disturbances from Wiener process W(t). |
mu0 |
A baseline mortality. |
theta |
A displacement coefficient. |
ystart |
A vector with length equal of k, defines starting values of covariates. |
tstart |
A number that defines starting time (30 by default). |
tend |
A number, defines final time (105 by default). |
dt |
A discrete step size between two observations. A random uniform value is then added to this step size. |
sd0 |
a standard deviation for modelling the next covariate value. |
nobs |
A number of observations (lines) for individual observations. |
gomp |
A flag (FALSE by default). When it is set, then time-dependent exponential form of mu0 and Q are used: mu0 = mu0*exp(theta*t). |
format |
Data format: "long" (default), "short". |
A table with simulated data.
Yashin, A.I. et al (2007). Stochastic model for analysis of longitudinal data on aging and mortality. Mathematical Biosciences, 208(2), 538-551.<DOI:10.1016/j.mbs.2006.11.006>.
library(stpm) dat <- simdata_cont(N=50) head(dat)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.