the data from which the plots are to be produced. In the default method the data can be specified as a list or data frame where each component is numeric, a numeric matrix, or a numeric vector. In the formula method, a symbolic specification of the form y ~ g can be given, indicating the observations in the vector y are to be grouped according to the levels of the factor g (the form y ~ 1 indicates no grouping). NAs are allowed in the data.
NOTE: When the formula method is used and the argument paired=TRUE (see below), the data in the vector y must have the same number of observations for each level of the factor g and for each level sorted in the same way according to the pairing variable.

for the formula method, a data.frame (or list) from which the variables in x should be taken.

for the formula method, an optional vector specifying a subset of observations to be used for plotting.

for the formula method, a function which indicates what should happen when the data contain NAs. The default is to ignore missing values in either the response or the group.

additional parameters passed to the default method, or by it to plot, points, axis, and title to control the appearance of the plot.

the method to be used to separate coincident points. When method="stack" coincident points are stacked, when method="jitter" coincident points are jittered, and when method="overplot" coincident points are overplotted. When there are 2 groups and paired=TRUE and paired.lines=TRUE the default value is method="overplot", otherewise the default method is method="stack" (which differs from the default value for the R function stripchart, which uses
method="overplot" by default).

when method="jitter" is used, the argument seed is passed to the R function set.seed. Since jittering depends on the R random number generator, using the same value of seed each time the same data are plotted with stripChart ensures that the resulting plot is the same.

when method="jitter" is used, jitter gives the amount of jittering applied.

when stacking is used, points are stacked this many line-heights (symbol widths) apart.

when vertical=TRUE (the default), the plots are drawn vertically rather than horizontally.

group labels which will be printed alongside (or underneath) each plot.

numeric scalar indicating the amount by which the group labels should be scaled relative to the default (see the help file for plot.default). The default is the current value of the graphics parameter cex.

when drop.unused.levels=TRUE, groups with no observations are dropped.

logical, if true add the chart to the current plot.

numeric vector giving the locations where the charts should be drawn, particularly when add=TRUE; defaults to 1:n where n is the number of groups.

plot limits: see plot.window.

labels: see title.

alternate way to specify axis labels. The dlab and glab labels may be used instead of xlab and ylab if those are not specified. dlab applies to the continuous data axis (the y-axis unless vertical=FALSE), and glab to the group axis.

on which axes to use a log scale: see plot.default.

Graphical parameters: see par.

Sets the cex value for the points plotted.

Axis control: see plot.default.

logical scalar indicating whether to plot the confidence interval. The default is show.ci=TRUE.

integer indicating which plotting character to use to indicate the estimate of location (mean or median) for each group (see the help file for plot.default). The default is location.pch=16, a filled circle.

numeric scalar giving the amount by which the plotting characters indicating the estimate of location for each group should be scaled relative to the default (see the help file for plot.default). The default is the current value of the graphics parameter cex.

numeric scalar between 0 and 1 indicating the confidence level associated with the confidence interval for the group location (population mean or median). The default value is conf.level=0.95.

integer indicating the minimum sample size required in order to plot a confidence interval for the group location. The default value is min.n.for.ci=2.

numeric scalar or vector of length equal to the number of groups (n) in units of cex indicating the amount of space between the line showing the confidence interval and tick mark associated with a particular group. The default value depends on the number of groups and is given by
3/ifelse(n > 2, (n-1)^(1/3), 1).

numeric scalar indicating the line width for the confidence interval bars. The default is the current value of the graphics parameter cex.

logical scalar indicating whether to add flat ends to the confidence interval bars. The default value is ci.bar.ends=TRUE.

numeric scalar in units of cxy indicating the size of confidence interval bar ends. The default value is half of the current value of cex.

logical scalar indicating with to add a gap between the estimate of group location and the confidence interval bar. The default value is ci.bar.gap=FALSE.

character string indicating whether and where to indicate the sample size for each group. Possible values are "bottom" (the default), "top", and "none".

integer indicating on which plot margin line to show the sample sizes for each group. The default value is n.text.line=2 when n.text="bottom" and 0 otherwise.

numeric scalar giving the amount by which the text indicating the sample size for each group should be scaled relative to the default (see the help file for
plot.default). The default is the current value of the graphics parameter cex.

character string indicating whether and where to indicate the estimates of location (mean or median) and scale (standard deviation or interquartile range) for each group. Possible values are "top" (the default), "bottom", and "none".

integer indicating the number of digits to round the estimates of location and scale. The default value is location.scale.digits=1.

integer passed to the function format indicating the the minimum number of digits to the right of the decimal point for the estimates of location and scale. The default value is the value of location.scale.digits, which forces all estimates of location and scale have the same number of digits to the right of the decimal point (including, possibly, trailing zeros). To omit trailing zeros, set nsmall=0.

integer indicating on which plot margin line to show the estimates of location and scale for each group. The default value is
location.scale.text.line=0 when n.text="top" and 3.5 otherwise.

numeric scalar giving the amount by which the text indicating the estimates of location and scale for each group should be scaled relative to the default (see the help file for plot.default). The default depends on the number of groups and is given by cex * 0.8 * ifelse(n > 6, max(0.4, 1 - (n-6) * 0.06), 1), where cex denotes the current value of the graphics parameter cex.

logical scalar indicating whether to show the p-value associated with testing whether all groups have the same population location. The default value is p.value=FALSE. The p-value is displayed at the top of the graph.

integer indicating the number of digits to round to when displaying the p-value associated with the test of equal group locations. The default value is
p.value.digits=3.

integer indicating on which plot margin line to show the p-value associated with the test of equal group locations. The default value is p.value.line=2.

numeric scalar giving the amount by which the text indicating the p-value associated with the test of equal group locations should be scaled relative to the default (see the help file for plot.default). The default is the current value of the graphics parameter cex.

for the case when there are just 2 groups, a logical scalar indicating whether to display the confidence interval for the difference between group locations. The default is the value of the p.value argument. The confidence interval is displayed at the top of the graph in the format [Lower CI, Upper CI].

for the case when there are just 2 groups, a numeric scalar between 0 and 1 indicating the confidence level associated with the confidence interval for the difference between group locations. The default is conf.level=0.95.

for the case when there are just 2 groups, an integer indicating the number of digits to round to when displaying the confidence interval for the difference between group locations. The default value is
group.difference.digits=location.scale.digits.

character string indicating whether confidence intervals and tests should be based on parametric or nonparametric (ci.and.test="nonparametric") methods. When ci.and.test="parametric" (the default), confidence intervals for the population mean are based on the one-sample t-test (see t.test), and the test of group differences is based on the two-sample t-test if there are two groups and the F-test (i.e., one-way analysis of variance, see aov) if there are three or more groups. When ci.and.test="nonparametric", confidence intervals for the population pseudo-median are based on the Wilcoxon signed rank test (see wilcox.test and page 56 of Hollander and Wolfe, 1999), and the test of group differences is based on the Wilcoxon rank sum test if there are two groups (see wilcox.test) and the Kruskal-Wallis test (see kruskal.test) if there are three or more groups.

an optional list of arguments to pass to the function used to compute confidence intervals. The default value is ci.arg.list=NULL.

an optional list of arguments to pass to the function used to test for group differences in location. The default value is test.arg.list=NULL. In particular, in the case when there are two groups, ci.and.test="parametric", and ci.arg.list is NULL or does not contain a component specifying the value for var.equal, this argument is updated to include the component var.equal=TRUE, which is not the default behavior of t.test.
NOTE: If test.arg.list contains a component named "paired", the value of that component is set to the value of the argument paired (see below).

character string describing the alternative hypothesis for the test of group differences in the case when there are two groups. Possible values are "two.sided" (the default), "less", and "greater".

applicable only to the case when there are two groups:
logical scalar indicating whether to plot the confidence interval for the difference between the groups. The default is plot.diff=FALSE.

When plot.diff=TRUE and paired=FALSE, the confidence interval for the difference between the two locations is displayed and the right-hand axis (when vertical=TRUE) or top axis (when vertical=FALSE) is labeled in units of the confidence interval for the difference between the two locations. If
ci.and.test="parametric", the confidence interval for the difference between the two means is displayed. If ci.and.test="nonparametric", the confidence interval for the median of the difference between a sample from the first group and a sample from the second group is displayed (see the help file for wilcox.test.

When plot.diff=TRUE and paired=TRUE, the paired differences are displayed and the right-hand axis (when vertical=TRUE) or top axis (when
vertical=FALSE) is labeled in units of the paired differences. In addition, if show.ci=TRUE, the confidence interval based on the paired differences is displayed. In this case, if ci.and.test="parametric" the confidence interval for the mean of the paired differences is displayed, and if
ci.and.test="nonparametric" the confidence interval for the pseudomedian is displayed (see the help file for wilcox.test.

applicable only to the case when there are two groups and plot.diff=TRUE:
numeric or character scalar indicating what color to use for the confidence interval for the difference in locations between the two groups. When paired=TRUE, this argument also controls the color of the paired differences. The default is diff.col=col[1].

applicable only to the case when there are two groups, plot.diff=TRUE, and paired=TRUE:
the method to be used to separate coincident points for the paired differences. The default value is diff.method="stack". Other options are
diff.method="jitter" and diff.method="overplot". See the explanation for the argument method above.

applicable only to the case when there are two groups, plot.diff=TRUE, and paired=TRUE:
numeric or character scalar indicating what plotting symbol to use for the paired differences. The default is diff.pch=pch[1].

applicable only to the case when there are two groups:
logical scalar indicating whether the observations in the first group are paired with those in the second group. The default is paired=FALSE.
NOTE 1: When the formula method for the argument x is used (see above) and the argument paired=TRUE, the data in the vector y must have the same number of observations for each level of the factor g and for each level sorted in the same way according to the pairing variable.
NOTE 2: If the argument test.arg.list (see above) contains a component named "paired", the value of that component is set to the value of the argument paired.

applicable only to the case when there are two groups and paired=TRUE:
logical scalar indicating whether to join the paired observations with lines. The default value is the value of the argument paired.

applicable only to the case when there are two groups, paired=TRUE, and
paired.lines=TRUE:
numeric vector indicating the line types to use to join the paired observations with lines. The default value is paired.lty=1:6.

applicable only to the case when there are two groups, paired=TRUE, and
paired.lines=TRUE:
numeric vector indicating the widths of the lines used to join the paired observations with lines. The default value is paired.lwd=1.

applicable only to the case when there are two groups, paired=TRUE, and
paired.lines=TRUE:
numeric vector indicating the plotting characters to use at each end of the lines used to join the paired observations with lines. The default value is
paired.pch=1:14.

applicable only to the case when there are two groups, paired=TRUE, and
paired.lines=TRUE:
character or numeric vector indicating the colors for the lines (and plotting characters) used to join the paired observations with lines. The default value is paired.col=NULL, in which case the vector becomes
c("black", "red", "green3", "blue", "magenta", "darkgreen",
"purple", "orange", "darkolivegreen", "steelblue", "darkgray").

applicable only to the case when there are two groups and plot.diff=TRUE:
character scalar indicating the label to use for the confidence interval for the difference between groups. For the case when paired=TRUE, this label also describes the paired differences. The default value is diff.name=NULL, in which case the label is "group 2 - group 1", where group 1 and group 2 denote the names for the each group. For example, if group 1 is labeled "A" and group 2 is labeled "B", then the default value is diff.name="B-A".

applicable only to the case when there are two groups and plot.diff=TRUE:
numeric scalar indicating the amount by which the label for group differences should be scaled relative to the default (see the help file for plot.default). The default value is diff.name.cex=group.names.cex.

applicable only to the case when there are two groups and plot.diff=TRUE:
logical scalar indicating whether to draw a line between the strip charts for the two groups and the confidence interval for the difference between the two groups (and paired differences when paired=TRUE). The default value is
sep.line=TRUE.

applicable only to the case when there are two groups, plot.diff=TRUE, and sep.line=TRUE:
numeric scalar indicating the line type to use for the line drawn between the strip charts for the two groups and the confidence interval for the difference between the two groups. The default value is sep.lty=2.

applicable only to the case when there are two groups, plot.diff=TRUE, and sep.line=TRUE:
numeric scalar indicating the line width to use for the line drawn between the strip charts for the two groups and the confidence interval for the difference between the two groups. The default value is the current value of the graphics parameter cex.

applicable only to the case when there are two groups, plot.diff=TRUE, and sep.line=TRUE:
numeric or character scalar indicating the color of the line drawn between the strip charts for the two groups and the confidence interval for the difference between the two groups. The default value is sep.col="gray".

applicable only to the case when there are two groups and plot.diff=TRUE:
numeric vector of length 2 indicating the limits to use for the axis associated with the confidence interval for the difference between the two groups. When paired=FALSE, the default value is the range of the y-axis, but centered at the mean of the confidence interval for the difference in locations. When
paired=TRUE, the default value is range(pretty(c(X, range(CI)))) where X denotes the vector containing the paired differences.

applicable only to the case when there are two groups and plot.diff=TRUE:
numeric vector indicating the locations of the tick marks for the axis associated with the confidence interval for the difference between groups (see the explanation for the argument at in the help file for axis). The default value is diff.at=NULL, in which case default values are used for the locations of the tick marks.

applicable only to the case when there are two groups and plot.diff=TRUE:
character string indicating the label to use for the axis associated with the confidence interval for the difference between groups. When paired=FALSE the default value is "Difference Between Groups", and when paired=TRUE the default value is "Paired Difference".

applicable only to the case when there are two groups, plot.diff=TRUE, and add=FALSE:
numeric vector of length 4 indicating the number of lines in the plotting margins (see the explanation for the argument mar in the help file for par). The default value is plot.diff.mar = c(5, 4, 4, 4) + 0.1.

numeric vector of values on the group axis (the x-axis unless vertical=FALSE) indicating the centers of the groups.

a matrix with the number of rows equal to the number of groups and six columns indicating the sample size of the group (N), the estimate of the group location parameter (Mean or Median), the estimate of the group scale (SD or IQR), the lower confidence limit for the group location parameter (LCL), the upper confidence limit for the group location parameter (UCL), and the confidence level associated with the confidence interval (Conf.Level)

numeric scalar indicating the p-value associated with the test of equal group locations.

numeric vector of two elements indicating the confidence interval for the difference between the group locations. Only present when there are two groups.