# plotmeans: Plot Group Means and Confidence Intervals In gplots: Various R Programming Tools for Plotting Data

 plotmeans R Documentation

## Plot Group Means and Confidence Intervals

### Description

Plot group means and confidence intervals.

### Usage

```plotmeans(formula, data=NULL, subset, na.action,
bars=TRUE, p=0.95, minsd=0, minbar, maxbar,
xlab=names(mf), ylab=names(mf), mean.labels=FALSE,
ci.label=FALSE, n.label=TRUE, text.n.label="n=",
digits=getOption("digits"), col="black", barwidth=1,
barcol="blue", connect=TRUE, ccol=
col, legends=names(means), xaxt, use.t=TRUE,
lwd=par("lwd"), ...)
```

### Arguments

 `formula` symbolic expression specifying the outcome (continuous) and grouping variable (factor). See lm() for details. `data` optional data frame containing the variables in the model. `subset` an optional vector specifying a subset of observations to be used in the fitting process. `na.action` a function which indicates what should happen when the data contain ‘NA’s. See lm() for details. `bars` a logical value indicating whether confidence interval bars should be plotted. Defaults to TRUE. `p` confidence level for error bars. Defaults to 0.95. `minsd` minumum permitted value for the standard deviation within each factor level. Any standard deviation estimates smaller than `minsd` will be replaced with `minsd`. Defaults to 0. `minbar` minumum allowed value for bar ends. If specified, values smaller than `minbar` will be replaced with `minbar`. `maxbar` maximum allowed value for bar ends. If specified, values larger than `maxbar` will be replaced with `maxbar`. `xlab` x-axis label. `ylab` y-axis label. `mean.labels` either a logical value indicating whether the circles representing the group means should be replaced with text giving the actual mean values or a vector containing labels to use instead. Defaults to FALSE. `ci.label` a logical value indicating whether text giving the actual interval end values should be placed at the end of each confidence interval bar. Defaults to FALSE. `n.label` a logical value indicating whether text giving the number of observations in each group should should be added to the plot. `text.n.label` Prefix text for labeling observation counts. Defaults to "n=". `digits` number of significant digits to use when displaying mean or confidince limit values. `col` color of cicles marking group means. Default is "black". `barwidth` linewidth of interval bars and end marks. Default is 1. `barcol` color of interval bars and end marks. Default is "blue". `connect` either a logical value indicating whether the means of each group should be connected by a line, or a list of vectors giving the index of bars that should be connected by a line. Defaults to TRUE. `ccol` color of lines used to connect means. Defaults to the same color as "col". `legends` vector containing strings used to label groups along the x axis. Defaults to group names. `xaxt` A character which specifies the axis type. Specifying ‘"n"’ causes an axis to be set up, but not plotted. `use.t` a logical value indicating whether the t distribution should be used to compute confidence intervals. If `TRUE`, the default, a t distribution will the correct number of degrees of freedom for each group be used. If `FALSE`, the a normal distribution will be used. `lwd` Width of connecting lines `...` optional plotting parameters.

### Author(s)

Gregory R. Warnes greg@warnes.net

`plotCI`, `boxplot`

### Examples

```  # library(gplots)
# show comparison with boxplot
data(state)
plotmeans(state.area ~ state.region)

# show some color and mean labels
plotmeans(state.area ~ state.region,
mean.labels=TRUE, digits=-3,
col="red", connect=FALSE)

# show how to specify which means should be connected
plotmeans(state.area ~ state.region, connect=list(1:2, 3:4),
ccol="red", pch=7 )

# more complicated example showing how to show an interaction
data(esoph)
par(las=2,                        # use perpendicular axis labels
mar=c(10.1,4.1,4.1,2.1),      # create enough space for long x labels
mgp=c(8,1,0)                  # move x axis legend down to avoid overlap
)
plotmeans(ncases/ncontrols ~ interaction(agegp , alcgp, sep ="   "),
connect=list(1:6,7:12,13:18,19:24),
barwidth=2,
col="dark green",
data=esoph,
xlab="Age Group and Alcohol Consumption",
ylab="# Cases / # Controls",
ylim = c(-.9,1.4),
main=c("Fraction of Cases for by Age and Alcohol Consumption",
"Ile-et-Vilaine Esophageal Cancer Study")
)
abline(v=c(6.5, 12.5, 18.5), lty=2)

```

gplots documentation built on April 25, 2022, 9:06 a.m.