Get group means and CIs (rcompanion::groupwiseMean) — rcompanion

Get group means and bootstrapped effect sizes from the rcompanion::groupwiseMean function. The function had to be taken separately from the package as the dependency is failing upon install of the current package.

From the original documentation: "Calculates means and confidence intervals for groups."

From: https://rcompanion.org/handbook/C_03.html

"For routine use, I recommend using bootstrapped confidence intervals, particularly the BCa or percentile methods (but...) by default, the function reports confidence intervals by the traditional method."

Usage

rcompanion_groupwiseMean(
  formula = NULL,
  data = NULL,
  var = NULL,
  group = NULL,
  trim = 0,
  na.rm = FALSE,
  conf = 0.95,
  R = 5000,
  boot = FALSE,
  traditional = TRUE,
  normal = FALSE,
  basic = FALSE,
  percentile = FALSE,
  bca = FALSE,
  digits = 3,
  ...
)

Arguments

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, NA values 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 trim is not 0, the traditional confidence interval will produce NA. Likewise, if there are NA values 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::boot.ci}.
basic: If TRUE, includes the basic confidence intervals for the group means by bootstrap. See {boot::boot.ci}.
percentile: If TRUE, includes the percentile confidence intervals for the group means by bootstrap. See {boot::boot.ci}.
bca: If TRUE, includes the BCa confidence intervals for the group means by bootstrap. See {boot::boot.ci}.
digits: The number of significant figures to use in output.
...: Other arguments passed to the boot function.

Value

A data frame of requested statistics by group.

Details

The input should include either formula and data; or data, var, and group. (See examples).

     Results for ungrouped (one-sample) data can be obtained by either
     setting the right side of the formula to 1, e.g.  y ~ 1, or by
     setting \code{group=NULL} when using \code{var}.

Note

The parsing of the formula is simplistic. The first variable on the left side is used as the measurement variable. The variables on the right side are used for the grouping variables.

     In general, it is advisable to handle \code{NA} values before
     using this function.
     With some options, the function may not handle missing values well,
     or in the manner desired by the user.
     In particular, if \code{bca=TRUE} and there are \code{NA} values,
     the function may fail.

     For a traditional method to calculate confidence intervals
     on trimmed means,
     see Rand Wilcox, Introduction to Robust Estimation and
     Hypothesis Testing.

References

https://rcompanion.org/handbook/C_03.html

Author

Salvatore Mangiafico, mangiafico@njaes.rutgers.edu

Examples

# \donttest{
### Example with formula notation
data(mtcars)
rcompanion_groupwiseMean(mpg ~ factor(cyl),
  data         = mtcars,
  traditional  = FALSE,
  percentile   = TRUE
)
#>   cyl  n Mean Conf.level Percentile.lower Percentile.upper
#> 1   4 11 26.7       0.95             24.1             29.1
#> 2   6  7 19.7       0.95             18.7             20.7
#> 3   8 14 15.1       0.95             13.7             16.4

# Example with variable notation
data(mtcars)
rcompanion_groupwiseMean(
  data = mtcars,
  var = "mpg",
  group = c("cyl", "am"),
  traditional = FALSE,
  percentile = TRUE
)
#>   cyl am  n Mean Conf.level Percentile.lower Percentile.upper
#> 1   4  0  3 22.9       0.95             21.5             24.4
#> 2   4  1  8 28.1       0.95             25.0             30.9
#> 3   6  0  4 19.1       0.95             18.0             20.6
#> 4   6  1  3 20.6       0.95             19.7             21.0
#> 5   8  0 12 15.0       0.95             13.5             16.5
#> 6   8  1  2 15.4       0.95             15.0             15.8
# }