Dyestuff {lme4} | R Documentation |
The Dyestuff
data frame provides the yield of dyestuff
(Naphthalene Black 12B) from 5 different preparations from each of 6
different batchs of an intermediate product (H-acid). The
Dyestuff2
data were generated data in the same structure but
with a large residual variance relative to the
batch variance.
data(Dyestuff)
Data frames, each with 30 observations on the following 2 variables.
Batch
a factor indicating the batch of the intermediate product from which the preparation was created.
Yield
the yield of dyestuff from the preparation (grams of standard color).
The Dyestuff
data are described in Davies and Goldsmith (1972)
as coming from
“an investigation to find out how much the
variation from batch to batch in the quality of an intermediate
product (H-acid) contributes to the variation in the yield of the
dyestuff (Naphthalene Black 12B) made from it. In the experiment six
samples of the intermediate, representing different batches of works
manufacture, were obtained, and five preparations of the dyestuff
were made in the laboratory from each sample. The equivalent yield
of each preparation as grams of standard colour was determined by
dye-trial.”
The Dyestuff2
data are described in Box and Tiao (1973) as
illustrating
“
the case where between-batches mean square is less than the
within-batches mean square. These data had to be constructed for
although examples of this sort undoubtably occur in practice, they
seem to be rarely published.”
O.L. Davies and P.L. Goldsmith (eds), Statistical Methods in Research and Production, 4th ed., Oliver and Boyd, (1972), section 6.4
G.E.P. Box and G.C. Tiao, Bayesian Inference in Statistical Analysis, Addison-Wesley, (1973), section 5.1.2
str(Dyestuff) dotplot(reorder(Batch, Yield) ~ Yield, Dyestuff, ylab = "Batch", jitter.y = TRUE, aspect = 0.3, type = c("p", "a")) dotplot(reorder(Batch, Yield) ~ Yield, Dyestuff2, ylab = "Batch", jitter.y = TRUE, aspect = 0.3, type = c("p", "a")) (fm1 <- lmer(Yield ~ 1|Batch, Dyestuff)) (fm2 <- lmer(Yield ~ 1|Batch, Dyestuff2))