Description

Data obtained from Gomez and Hazen (1970, Tables 19 and 20) on coal ash for the Robena Mine Property in Greene County Pennsylvania.

Usage

Format

This data frame contains the following columns:

x

a numeric vector; x-coordinate; reference unknown

y

a numeric vector; x-coordinate; reference unknown

coalash

the target variable

Note

data are also present in package fields, as coalash.

Author(s)

unknown; R version prepared by Edzer Pebesma; data obtained from http://homepage.divms.uiowa.edu/~dzimmer/spatialstats/, Dale Zimmerman's course page

References

N.A.C. Cressie, 1993, Statistics for Spatial Data, Wiley.

Gomez, M. and Hazen, K. (1970). Evaluating sulfur and ash distribution in coal seems by statistical response surface regression analysis. U.S. Bureau of Mines Report RI 7377.

see also fields manual: http://www.image.ucar.edu/GSP/Software/Fields/fields.manual.coalashEX.Krig.shtml

Examples