Surface area of silica
Measurements of the surface area (m^2/g) of three batches of silica as performed by four different lab technicians.
A data frame with 12 observations on the following 3 variables.
batcha factor with levels a, b and c
techa factor with levels A, B, C
and D
sareathe surface area in m^2/g as measured by the lab technician on a sample from the batch
Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)
str(sarea)
xtabs(sarea ~ batch + tech, sarea)
dotplot(reorder(tech, sarea) ~ sarea, sarea,
groups = batch, type = c("p","a"), aspect = "xy",
ylab = "Technician",
xlab = expression("Measured surface area " * (m^2/g) *
" of silica batches"),
auto.key = list(columns = 3, lines = TRUE)
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