groupwiseMean: Groupwise means and confidence intervals

In rcompanion: Functions to Support Extension Education Program Evaluation

Groupwise means and confidence intervals

Description

Calculates means and confidence intervals for groups.

Usage

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.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 boot function.

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 group=NULL when using var.

Value

A data frame of requested statistics by group.

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 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 bca=TRUE and there are 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.

Author(s)

Salvatore Mangiafico, [e-mail]

References

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

See Also

groupwiseMedian, groupwiseHuber, groupwiseGeometric

Examples

### Example with formula notation
data(Catbus)
groupwiseMean(Steps ~ Teacher + Gender,
              data        = Catbus,
              traditional = FALSE,
              percentile  = TRUE)

### Example with variable notation
data(Catbus)
groupwiseMean(data        = Catbus,
              var         = "Steps",
              group       = c("Teacher", "Gender"),
              traditional = FALSE,
              percentile  = TRUE)
                                     

rcompanion documentation built on Sept. 17, 2023, 5:07 p.m.