law {bootstrap} | R Documentation |
Law school data from Efron and Tibshirani
Description
The law school data. A random sample of size from the
universe of 82 USA law schools. Two measurements: LSAT
(average score on
a national law test) and GPA (average undergraduate
grade-point average).
law82
contains data for the whole universe of 82 law schools.
Usage
data(law)
Format
A data frame with 15 observations on the following 2 variables.
- LSAT
a numeric vector
- GPA
a numeric vector
Details
In the book for which this package is support software, this example is used to bootstrap the correlation coefficient.
Source
Efron, B. and Tibshirani, R. (1993) An Introduction to the Bootstrap. Chapman and Hall, New York, London.
See Also
Examples
str(law)
if(interactive())par(ask=TRUE)
plot(law)
theta <- function(ind) cor(law[ind,1], law[ind,2])
theta(1:15) # sample estimate
law.boot <- bootstrap(1:15, 2000, theta)
sd(law.boot$thetastar) # bootstrap standard error
hist(law.boot$thetastar)
# bootstrap t confidence limits for the correlation coefficient:
theta <- function(ind) cor(law[ind,1], law[ind,2])
boott(1:15, theta, VS=FALSE)$confpoints
boott(1:15, theta, VS=TRUE)$confpoints
# Observe the difference! See page 162 of the book.
# abcnon(as.matrix(law), function(p,x) cov.wt(x, p, cor=TRUE)$cor[1,2] )$limits
# The above cannot be used, as the resampling vector can take negative values!
[Package bootstrap version 2019.6 Index]