wafer
AT&T Wafer Experiment

### Description

The wafer data frame has 18 rows and 13 columns, of which 8 contain factors, 4 contain responses, and one is the auxiliary variable N . It is a design object based on an orthogonal-array design for an experiment in which two integrated circuit wafers were made for each combination of factors, and on each wafer the pre- and post-etch line widths were measured five times. The response variables are the mean and deviance of the measurements. As 3 of the wafers were broken, the auxiliary variable N gives the number of measurements actually made. This data frame contains the following columns:

### Arguments

maskdim | ordered factor with the inheritance attribute "category" , levels are 2 < 2.5
visc.tem | factor, levels are 204,90 , 206,90 , and 204,105
spinsp | ordered factor with the inheritance attribute "category" , levels are low < normal < high.
baketime | ordered factor with the inheritance attribute "category" , levels are 20 < 30 < 40.
aperture | factor, levels are 1 , 2 , and 3 .
exptime | ordered factor with the inheritance attribute "category" , levels are `-20% < normal < +20%'.
devtime | an ordered factor with the inheritance attribute "category" , levels are ` 30 < 45 < 60'.
etchtime | ordered factor with the inheritance attribute "category" , levels are ` 13.2 < 14.5 < 15.8'.
pre.mean | numeric vector giving the mean of the pre-etch line width
pre.dev | numeric vector giving the deviance of the pre-etch line width
post.mean | numeric vector giving the mean of the post-etch line width
post.dev | numeric vector giving the deviance of the post-etch line width
N | numeric vector giving the number of measurements.

Source
Phadke, M.S., Kackar, R.N., Speene, D.V., and Grieco, M.J. (1983) Off-line Quality Control in Integrated Circuit Fabrication Using Experimental Design. Bell System Technical Journal Vol. 62, pp. 1273--309.
John M. Chambers and Trevor J. Hastie, (eds.) Statistical Models in S, Wadsworth and Brooks, Pacific Grove, CA 1992, pg. 147.
Examples

    data(wafer)
    wpm <- wafer[, c(1:9)]
    waov1 <- aov(pre.mean ~ . , wpm)

Package Sdatasets version 6.1.5-18
Package Index