errorCircles {psych} R Documentation

Two way plots of means, error bars, and sample sizes

Description

Given a matrix or data frame, data, find statistics based upon a grouping variable and then plot x and y means with error bars for each value of the grouping variable. If the data are paired (e.g. by gender), then plot means and error bars for the two groups on all variables.

Usage

errorCircles(x, y, data, ydata = NULL, group=NULL, paired = FALSE, labels = NULL,
main = NULL, xlim = NULL, ylim = NULL, xlab = NULL, ylab = NULL,add=FALSE, pos = NULL,
offset = 1, arrow.len = 0.2, alpha = 0.05, sd = FALSE, bars = TRUE, circles = TRUE, ...)

Arguments

 x The x variable (by name or number) to plot y The y variable (name or number) to plot data The matrix or data.frame to use for the x data ydata If plotting data from two data.frames, then the y variable of the ydata frame will be used. group If specified, then statsBy is called first to find the statistics by group paired If TRUE, plot all x and y variables for the two values of the grouping variable. labels Variable names main Main title for plot xlim xlim values if desired– defaults to min and max mean(x) +/- 2 se ylim ylim values if desired – defaults to min and max mean(y) +/- 2 se xlab label for x axis – grouping variable 1 ylab label for y axis – grouping variable 2 add If TRUE, add to the prior plot pos Labels are located where with respect to the mean? offset Labels are then offset from this location arrow.len Arrow length alpha alpha level of error bars sd if sd is TRUE, then draw means +/- 1 sd) bars Should error.bars be drawn for both x and y circles Should circles representing the relative sample sizes be drawn? ... Other parameters for plot

Details

When visualizing the effect of an experimental manipulation or the relationship of multiple groups, it is convenient to plot their means as well as their confidence regions in a two dimensional space.

Value

If the group variable is specified, then the statistics from statsBy are (invisibly) returned.

Note

Basically this is a combination (and improvement) of statsBy with error.crosses. Can also serve some of the functionality of error.bars.by (see the last example).

William Revelle

Examples

#BFI scores for males and females
errorCircles(1:25,1:25,data=bfi,group="gender",paired=TRUE,ylab="female scores",
xlab="male scores",main="BFI scores by gender")
abline(a=0,b=1)
#drop the circles since all samples are the same sizes
errorCircles(1:25,1:25,data=bfi,group="gender",paired=TRUE,circles=FALSE,
ylab="female scores",xlab="male scores",main="BFI scores by gender")
abline(a=0,b=1)

data(affect)
colors <- c("black","red","white","blue")
affect.stats <- errorCircles("EA2","TA2",data=affect,group="Film",labels=films,
xlab="Energetic Arousal",ylab="Tense Arousal",ylim=c(10,22),xlim=c(8,20),
pch=16,cex=2,col=colors, main ="EA and TA pre and post affective movies")
#now, use the stats from the prior run