boot {CarletonStats}

Bootstrap

Description

Bootstrap a single variable or a grouped variable

Usage

boot(x, ...)

## Default S3 method:
boot(
  x,
  group = NULL,
  statistic = mean,
  conf.level = 0.95,
  B = 10000,
  plot.hist = TRUE,
  plot.qq = FALSE,
  x.name = deparse(substitute(x)),
  xlab = NULL,
  ylab = NULL,
  title = NULL,
  seed = NULL,
  ...
)

## S3 method for class 'formula'
boot(formula, data, subset, ...)

Arguments

x

a numeric vector

...

further arguments to be passed to or from methods.

group

an optional grouping variable (vector), usually a factor variable. If it is a binary numeric variable, it will be coerced to a factor.

statistic

function that computes the statistic of interest. Default is the mean.

conf.level

confidence level for the bootstrap percentile interval. Default is 95%.

B

number of times to resample (positive integer greater than 2).

plot.hist

logical value. If TRUE, plot the histogram of the bootstrap distribution.

plot.qq

Logical value. If TRUE, create a normal quantile-quantile plot of the bootstrap distribution.

x.name

Label for variable name

xlab

an optional character string for the x-axis label

ylab

an optional character string for the y-axis label

title

an optional character string giving the plot title

seed

optional argument to set.seed

formula

a formula y ~ g where y is a numeric vector and g a factor variable with two levels. If g is a binary numeric vector, it will be coerced to a factor variable. For a single numeric variable, formula may also be ~ y.

data

a data frame that contains the variables given in the formula.

subset

an optional expression indicating what observations to use.

Details

Perform a bootstrap of a statistic applied to a single variable, or to the difference of the statistic computed on two samples (using the grouping variable). If x is a binary vector of 0's and 1's and the function is the mean, then the statistic of interest is the proportion.

Observations with missing values are removed.

Value

A vector with the resampled statistics is returned invisibly.

Methods (by class)

• boot(default): Bootstrap a single variable or a grouped variable

• boot(formula): Bootstrap a single variable or a grouped variable

Author(s)

Laura Chihara

References

Tim Hesterberg's website https://www.timhesterberg.net/bootstrap-and-resampling

Examples

#ToothGrowth data (supplied by R)
#bootstrap mean of a single numeric variable
boot(ToothGrowth$len)

#bootstrap difference in mean of tooth length for two groups.
boot(ToothGrowth$len, ToothGrowth$supp, B = 1000)

#same as above using formula syntax
boot(len ~ supp, data = ToothGrowth, B = 1000)