ez: ezResample – R documentation

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ezResample

Resample data from a factorial experiment

Description

This function resamples data (useful when bootstrapping and used by ezBoot).

Usage

ezResample(
    data
    , wid
    , within = NULL
    , between = NULL
    , resample_within = FALSE
    , resample_between = TRUE
    , check_args = TRUE
)

Arguments

`data`	Data frame containing the data to be analyzed.
`wid`	.() object specifying the column in `data` that contains the variable specifying the case/Ss identifier.
`within`	Optional .() object specifying one or more columns in `data` that contain predictor variables that are manipulated (or observed) within-Ss.
`between`	Optional .() object specifying one or more columns in `data` that contain predictor variables that are manipulated (or observed) between-Ss.
`resample_within`	Logical. If TRUE, and if there are multiple observations per subject within each cell of the design specified by the factorial combination of variables supplied to `within` and `between`, then these observations-within-cells are resampled with replacement.
`resample_between`	Logical. If TRUE (default), levels of `wid` are resampled.
`check_args`	Users should leave this as its default (TRUE) value. This argument is intended for internal use only.

Value

A data frame consisting of the resampled data

Author(s)

Michael A. Lawrence mike.lwrnc@gmail.com
Visit the ez development site at http://github.com/mike-lawrence/ez
for the bug/issue tracker and the link to the mailing list.

Examples

library(plyr)
#Read in the ANT data (see ?ANT).
data(ANT)
head(ANT)
ezPrecis(ANT)


#Bootstrap the within-cell variances
var_boots = ldply(
    .data = 1:1e1 #1e3 or higher should be used for publication
    , .fun = function(x){
        this_resample = ezResample(
            data = ANT[ANT$error==0,]
            , wid = .(subnum)
            , within = .(cue,flank)
            , between = .(group)
        )
        cell_vars = ddply(
            .data = idata.frame(this_resample)
            , .variables = .(subnum,cue,flank,group)
            , .fun = function(x){
                to_return = data.frame(
                    value = var(x$rt)
                )
                return(to_return)
            }
        )
        mean_cell_vars = ddply(
            .data = idata.frame(cell_vars)
            , .variables = .(cue,flank,group)
            , .fun = function(x){
                to_return = data.frame(
                    value = mean(x$value)
                )
                return(to_return)
            }
        )
        mean_cell_vars$iteration = x
        return(mean_cell_vars)
    }
    , .progress = 'time'
)

ez

Easy Analysis and Visualization of Factorial Experiments

v4.4-0

GPL (>= 2)

Authors

Michael A. Lawrence <mike.lwrnc@gmail.com>

Initial release

2016-11-01