spdgp (version 0.1.0)

sim_sem: Simulate Spatial Error Model (SEM)

Description

Simulate the y values for an SEM model.

Usage

sim_sem(u, xb, listw, lambda = 0.5, model = c("sar", "ma"))

Value

A numeric vector

Arguments

u

an error vector

xb

predicted x values as calculated by make_xb()

listw

a listw object generated with sim_grid_listw().

lambda

a value value between -1 and 1. The spatial autoregressive coefficient for the error term.

model

default "sar". Which model should be simulated. Provide "ma" for the moving average.

References

spreg.dgp.dgp_sperror

Examples

ncol <- 10
n <- ncol^2
listw <- sim_grid_listw(ncol, ncol)  # Create spatial weights for a grid
u <- make_error(n)  # Simulate random errors
x <- make_x(
  n,
  mu = c(0.25, 5),
  var = c(1, 0.75),
  method = "normal"
)  # Generate x variables

# create xb with intercept = 1, beta1 = 2, beta2 = -3
xb <- make_xb(x, c(1, 2, -3))
y <- sim_sem(u, xb, listw)

# combine data 
df <- cbind(y = y, x)

# fit SEM model
# Note lambda, x_1, and x_2 estimates.
spatialreg::errorsarlm(y ~ ., df, listw)