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In-Depth Information
that these differences in slope are not significant. hat is, the three-factor interaction
is not statistically significant. he boxplots in Fig.
.
are all based on samples of
size
. Such boxplots are a well-defined but uncustomary way to display such a sam-
ple.
Sequences of Boxplots
6.7.2
A recent comparative clinical trial at GlaxoSmithKline (Amit et al.,
) examined
the result of monitoring
ASAT
in two
trt
groups
A
and
B
ater
,
,
,
,
,
, and
weeks. ASAT and other clinical biochemistry laboratory blood assays were mon-
itored to give an early signal of potential adverse events in liver function in response
to the treatments. he sample size for treatment
A
was about
patients and for
treatment
B
about
. ASAT (aspartate aminotransferase), an enzyme associated
with liver parenchymal cells, is raised in acute liver damage. he display in Fig.
.
Figure
.
.
Comparative distributions of responses of two treatment groups at unequally spaced
points in time. Boxplots are color coded to distinguish between the two treatment groups. he covariate
time is correctly scaled on the horizontal axis. Since the data are positively skewed with extreme
outliers and with missing values, we choose to truncate observations at
asat
=
in order to display
full details on the bulk of the data. he sample sizes and numbers of missing and outlying observations
are noted on the graph (File: h
/intx/code/lt.asat.s)
