Description Usage Format Source Examples
Measurements in the bone mineral density of 261 north american adolescents, as function of age. Each value is the difference in spnbmd taken on two consecutive visits, divided by the average. The age is the average age over the two visits.
1 |
A data frame with 485 observations on the following 4 variables.
identifies the child, and hence the repeat measurements
average of age at two visits
a factor with levels female
male
Relative Spinal bone mineral density measurement
Bachrach LK, Hastie T, Wang M-C, Narasimhan B, Marcus R. Bone Mineral Acquisition in Healthy Asian, Hispanic, Black and Caucasian Youth. A Longitudinal Study. J Clin Endocrinol Metab (1999) 84, 4702-12.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | summary(bone)
# We ignore the repeat measurements:
# smooth.spline is in standard package stats.
names(bone)
# Plot page 128 in the book:
plot(spnbmd ~ age, data=bone, col =
ifelse(gender=="male", "blue", "red2"),
xlab="Age", ylab="Relative Change in Spinal BMD")
bone.spline.male <- with(subset(bone,gender=="male"),
smooth.spline(age, spnbmd,df=12))
bone.spline.female <- with(subset(bone, gender=="female"),
smooth.spline(age, spnbmd, df=12))
lines(bone.spline.male, col="blue")
lines(bone.spline.female, col="red2")
legend(20,0.20, legend=c("male", "Female"), col=c("blue", "red2"),
lwd=2)
|
idnum age gender spnbmd
Min. : 1.0 Min. : 9.40 female:259 Min. :-0.064103
1st Qu.: 60.0 1st Qu.:12.70 male :226 1st Qu.: 0.005858
Median :124.0 Median :15.40 Median : 0.026591
Mean :151.5 Mean :16.10 Mean : 0.039252
3rd Qu.:240.0 3rd Qu.:19.15 3rd Qu.: 0.064127
Max. :384.0 Max. :25.55 Max. : 0.219913
[1] "idnum" "age" "gender" "spnbmd"
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