stsls {spdep}R Documentation

Generalized spatial two stage least squares

Description

The function fits a spatial lag model by two stage least squares, with the option of adjusting the results for heteroskedasticity.

Usage

stsls(formula, data = list(), listw, zero.policy = FALSE,
 na.action = na.fail, robust = FALSE)

Arguments

formula a symbolic description of the model to be fit. The details of model specification are given for lm()
data an optional data frame containing the variables in the model. By default the variables are taken from the environment which the function is called.
listw a listw object created for example by nb2listw
zero.policy if TRUE assign zero to the lagged value of zones without neighbours, if FALSE (default) assign NA - causing lagsarlm() to terminate with an error
na.action a function (default na.fail), can also be na.omit or na.exclude with consequences for residuals and fitted values - in these cases the weights list will be subsetted to remove NAs in the data. It may be necessary to set zero.policy to TRUE because this subsetting may create no-neighbour observations. Note that only weights lists created without using the glist argument to nb2listw may be subsetted.
robust default FALSE, if TRUE, apply a heteroskedasticity correction to the coefficient estimatess and their covariances

Details

The fitting implementation fits a spatial lag model:

y = rho W y + X beta + e

by using spatially lagged X variables as instruments for the spatially lagged dependent variable.

Value

an object of class "stsls" containing:

coefficients coefficient estimates
var coefficient covariance matrix
sse sum of squared errors
residuals model residuals
df degrees of freedom

Author(s)

Luc Anselin and Roger Bivand

References

Kelejian, H.H. and I.R. Prucha (1998). A generalized spatial two stage least squares procedure for estimating a spatial autoregressive model with autoregressive disturbances. Journal of Real Estate Finance and Economics 17, 99-121.

See Also

lagsarlm

Examples

data(oldcol)
COL.lag.eig <- lagsarlm(CRIME ~ INC + HOVAL, data=COL.OLD, nb2listw(COL.nb))
summary(COL.lag.eig, correlation=TRUE)
COL.lag.stsls <- stsls(CRIME ~ INC + HOVAL, data=COL.OLD, nb2listw(COL.nb))
summary(COL.lag.stsls, correlation=TRUE)
COL.lag.stslsR <- stsls(CRIME ~ INC + HOVAL, data=COL.OLD, nb2listw(COL.nb),
robust=TRUE)
summary(COL.lag.stslsR, correlation=TRUE)
data(boston)
gp2a <- stsls(log(CMEDV) ~ CRIM + ZN + INDUS + CHAS + I(NOX^2) + I(RM^2) +
  AGE + log(DIS) + log(RAD) + TAX + PTRATIO + B + log(LSTAT),
 data=boston.c, nb2listw(boston.soi))
summary(gp2a)

[Package spdep version 0.4-34 Index]