Data on the body and brain weights of 20 mice, together
with the size of the litter. Two mice were taken from each
litter size.
Usage
litters
Format
This data frame contains the following columns:
lsize
litter size
bodywt
body weight
brainwt
brain weight
Source
Wainright P, Pelkman C and Wahlsten D 1989. The quantitative
relationship between nutritional effects on preweaning growth
and behavioral development in mice. Developmental Psychobiology
22: 183-193.
Examples
print("Multiple Regression - Example 6.2")
pairs(litters, labels=c("lsize\n\n(litter size)", "bodywt\n\n(Body Weight)",
"brainwt\n\n(Brain Weight)"))
# pairs(litters) gives a scatterplot matrix with less adequate labeling
mice1.lm <- lm(brainwt ~ lsize, data = litters) # Regress on lsize
mice2.lm <- lm(brainwt ~ bodywt, data = litters) #Regress on bodywt
mice12.lm <- lm(brainwt ~ lsize + bodywt, data = litters) # Regress on lsize & bodywt
summary(mice1.lm)$coef # Similarly for other coefficients.
# results are consistent with the biological concept of brain sparing
pause()
hat(model.matrix(mice12.lm)) # hat diagonal
pause()
plot(lm.influence(mice12.lm)$hat, residuals(mice12.lm))
print("Diagnostics - Example 6.3")
mice12.lm <- lm(brainwt ~ bodywt+lsize, data=litters)
oldpar <-par(mfrow = c(1,2))
bx <- mice12.lm$coef[2]; bz <- mice12.lm$coef[3]
res <- residuals(mice12.lm)
plot(litters$bodywt, bx*litters$bodywt+res, xlab="Body weight",
ylab="Component + Residual")
panel.smooth(litters$bodywt, bx*litters$bodywt+res) # Overlay
plot(litters$lsize, bz*litters$lsize+res, xlab="Litter size",
ylab="Component + Residual")
panel.smooth(litters$lsize, bz*litters$lsize+res)
par(oldpar)
Results
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> library(DAAG)
Loading required package: lattice
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/DAAG/litters.Rd_%03d_medium.png", width=480, height=480)
> ### Name: litters
> ### Title: Mouse Litters
> ### Aliases: litters
> ### Keywords: datasets
>
> ### ** Examples
>
> print("Multiple Regression - Example 6.2")
[1] "Multiple Regression - Example 6.2"
>
> pairs(litters, labels=c("lsize\n\n(litter size)", "bodywt\n\n(Body Weight)",
+ "brainwt\n\n(Brain Weight)"))
> # pairs(litters) gives a scatterplot matrix with less adequate labeling
>
> mice1.lm <- lm(brainwt ~ lsize, data = litters) # Regress on lsize
> mice2.lm <- lm(brainwt ~ bodywt, data = litters) #Regress on bodywt
> mice12.lm <- lm(brainwt ~ lsize + bodywt, data = litters) # Regress on lsize & bodywt
>
> summary(mice1.lm)$coef # Similarly for other coefficients.
Estimate Std. Error t value Pr(>|t|)
(Intercept) 0.447000000 0.009624762 46.442707 3.391193e-20
lsize -0.004033333 0.001198423 -3.365534 3.444524e-03
> # results are consistent with the biological concept of brain sparing
>
> pause()
>
> hat(model.matrix(mice12.lm)) # hat diagonal
[1] 0.19909923 0.17342736 0.13029307 0.15735137 0.08787909 0.27318075
[7] 0.06765524 0.06934443 0.15549909 0.09469559 0.12792400 0.07573376
[13] 0.13967323 0.07334975 0.12506629 0.08791076 0.43260877 0.12585659
[19] 0.20416791 0.19928375
> pause()
>
> plot(lm.influence(mice12.lm)$hat, residuals(mice12.lm))
>
> print("Diagnostics - Example 6.3")
[1] "Diagnostics - Example 6.3"
>
> mice12.lm <- lm(brainwt ~ bodywt+lsize, data=litters)
> oldpar <-par(mfrow = c(1,2))
> bx <- mice12.lm$coef[2]; bz <- mice12.lm$coef[3]
> res <- residuals(mice12.lm)
> plot(litters$bodywt, bx*litters$bodywt+res, xlab="Body weight",
+ ylab="Component + Residual")
> panel.smooth(litters$bodywt, bx*litters$bodywt+res) # Overlay
> plot(litters$lsize, bz*litters$lsize+res, xlab="Litter size",
+ ylab="Component + Residual")
> panel.smooth(litters$lsize, bz*litters$lsize+res)
> par(oldpar)
>
>
>
>
>
> dev.off()
null device
1
>