Oxide layer thicknesses on semiconductors

Description

The Semi2 data frame has 72 rows and 5 columns.

Format

This data frame contains the following columns:

Source

a factor with levels 1 and 2

Lot

a factor with levels 1 to 8

Wafer

a factor with levels 1 to 3

Site

a factor with levels 1 to 3

Thickness

a numeric vector

Source

Littel, R. C., Milliken, G. A., Stroup, W. W., and Wolfinger, R. D. (1996), SAS System for Mixed Models, SAS Institute (Data Set 4.4).

Examples

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str(Semi2)
xtabs(~Lot + Wafer, Semi2)
if (require("lme4", quietly = TRUE, character = TRUE)) {
  options(contrasts = c(unordered = "contr.SAS", ordered = "contr.poly"))
  ## compare with output 4.13, p. 156
  print(fm1Semi2 <- lmer(Thickness ~ 1 + (1|Lot/Wafer), Semi2))
  ## compare with output 4.15, p. 159
  print(fm2Semi2 <- lmer(Thickness ~ Source + (1|Lot/Wafer), Semi2))
  print(anova(fm2Semi2))
  ## compare with output 4.17, p. 163
  print(fm3Semi2 <- lmer(Thickness ~ Source + (1|Lot/Wafer) + (1|Lot:Source),
                         Semi2))
  ## This is not the same as the SAS model.
}