R: Coal ash in mining samples

coalash {sm} | R Documentation

## Coal ash in mining samples

### Description

These data record the percentage of coal ash found in mining samples originally reported by Gomez and Hazen (1970) and subsequently used by Cressie (1993).

The variables are:

`East` | a code for east-west direction
`North` | a code for north-south direction
`Percent` | the percentage of coalash

Cressie, N. (1993). Statistics for Spatial Data, revised edition. New York: Wiley.

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

[Package sm version 2.2-5.4 Index]