Missouri {RcppCensSpatial}

TCDD concentration data

Description

The level of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD) data was collected in November 1983 by the U.S. Environmental Protection Agency (EPA) in several areas of a highway in Missouri, USA. The TCDD measurement was subject to a limit of detection (cens); thereby, the TCDD data is left-censored. Only the locations used in the geostatistical analysis by Zirschky and Harris (1986) are shown.

Usage

data("Missouri")

Format

A data frame with 127 observations and five variables:

xcoord

x coordinate of the start of each transect (ft).

ycoord

y coordinate of the start of each transect (ft).

TCDD

TCDD concentrations (mg/kg).

transect

transect length (ft).

cens

indicator of censoring (left-censored observations).

Source

Zirschky JH, Harris DJ (1986). “Geostatistical analysis of hazardous waste site data.” Journal of Environmental Engineering, 112(4), 770–784.

See Also

EM.sclm, MCEM.sclm, SAEM.sclm

Examples

data("Missouri")
y = log(Missouri$TCDD)
cc = Missouri$cens
coord = cbind(Missouri$xcoord/100, Missouri$ycoord)
x = matrix(1, length(y), 1)
lcl = rep(-Inf, length(y))
ucl = y

## SAEM fit
set.seed(83789)
fit1 = SAEM.sclm(y, x, cc, lcl, ucl, coord, 5, 1, lower=c(1e-5,1e-5),
                 upper=c(50,50))
fit1$tab

## MCEM fit
fit2 = MCEM.sclm(y, x, cc, lcl, ucl, coord, 5, 1, lower=c(1e-5,1e-5),
                 upper=c(50,50), MaxIter=300, nMax=1000)
fit2$tab

## Imputed values
cbind(fit1$EY, fit2$EY)[cc==1,]