The semicond data frame has 48 rows and 5 columns.
This data frame contains the following columns:
a numeric vector
a factor with levels 1 to 4 representing etch time.
a factor with levels 1 to 3
a factor with levels 1 to 4
an ordered factor with levels
1/1 < 1/2 < 1/3 < 2/1 < 2/2 < 2/3 < 3/1 < 3/2 < 3/3 < 4/1 < 4/2 < 4/3
Also found in the SASmixed package