scor {bootstrap} R Documentation

## Open/Closed Book Examination Data

### Description

This is data form mardia, Kent and Bibby on 88 students who took examinations in 5 subjects. Some where with open book and other with closed book.

### Usage

`data(scor)`

### Format

A data frame with 88 observations on the following 5 variables.

mec

mechanics, closed book note

vec

vectors, closed book note

alg

algebra, open book note

ana

analysis, open book note

sta

statistics, open book note

### Details

The book uses this for bootstrap in principal component analysis.

### Source

Efron, B. and Tibshirani, R. (1993) An Introduction to the Bootstrap. Chapman and Hall, New York, London.

### Examples

```str(scor)
plot(scor)
# The parameter of interest (theta) is the fraction of variance explained
# by the first principal component.
# For principal components analysis svd is better numerically than
# eigen-decomposistion, but for bootstrapping the latter is _much_ faster.
theta <- function(ind) {
vals <- eigen(var(scor[ind,]), symmetric=TRUE, only.values=TRUE)\$values
vals[1] / sum(vals) }
scor.boot <- bootstrap(1:88, 500, theta)
sd(scor.boot\$thetastar) # bootstrap standard error
hist(scor.boot\$thetastar)
abline(v=theta(1:88), col="red2")
abline(v=mean(scor.boot\$thetastar), col="blue")
```

[Package bootstrap version 2019.6 Index]