- formula
- A formula indicating the measurement variable and
the grouping variables. e.g. y ~ x1 + x2. 
- data
- The data frame to use. 
- var
- The measurement variable to use. The name is in double quotes. 
- group
- The grouping variable to use. The name is in double quotes.
Multiple names are listed as a vector. (See example.) 
- trim
- The proportion of observations trimmed from each end of the
values before the mean is calculated. (As in - mean())
 
- na.rm
- If - TRUE,- NAvalues are removed during 
calculations. (As in- mean())
 
- conf
- The confidence interval to use. 
- R
- The number of bootstrap replicates to use for bootstrapped
statistics. 
- boot
- If - TRUE, includes the mean of the bootstrapped means.
This can be used as an estimate of the mean for
the group.
 
- traditional
- If - TRUE, includes the traditional confidence
intervals for the group means, using the t-distribution.
If- trimis not 0, 
the traditional confidence interval
will produce- NA.
Likewise, if there are- NAvalues that are not
removed, the traditional confidence interval
will produce- NA.
 
- normal
- If - TRUE, includes the normal confidence
intervals for the group means by bootstrap.
See- boot.ci.
 
- basic
- If - TRUE, includes the basic confidence
intervals for the group means by bootstrap.
See- boot.ci.
 
- percentile
- If - TRUE, includes the percentile confidence
intervals for the group means by bootstrap.
See- boot.ci.
 
- bca
- If - TRUE, includes the BCa confidence
intervals for the group means by bootstrap.
See- boot.ci.
 
- digits
- The number of significant figures to use in output. 
- ...
- Other arguments passed to the - bootfunction.