groupwiseMean {rcompanion}

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)