groupwiseGeometric: Groupwise geometric means and confidence intervals

In rcompanion: Functions to Support Extension Education Program Evaluation

Groupwise geometric means and confidence intervals

Description

Calculates geometric means and confidence intervals for groups.

Usage

groupwiseGeometric(
  formula = NULL,
  data = NULL,
  var = NULL,
  group = NULL,
  conf = 0.95,
  na.rm = TRUE,
  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.)
conf	The confidence interval to use.
na.rm	If TRUE, removes NA values in the measurement variable.
digits	The number of significant figures to use in output.
...	Other arguments. Not currently used.

Details

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

The function computes means, standard deviations, standard errors, and confidence intervals on log-transformed values. Confidence intervals are calculated in the traditional manner with the t-distribution on the transformed values, and then back-transforms the confidence interval limits. These statistics assume that the data are log-normally distributed. For data not meeting this assumption, medians and confidence intervals by bootstrap may be more appropriate.

Value

A data frame of geometric means, standard deviations, standard errors, and confidence intervals.

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.

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.

Author(s)

Salvatore Mangiafico, [e-mail]

References

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

See Also

groupwiseMean, groupwiseMedian, groupwiseHuber

Examples

### Example with formula notation 
data(Catbus)
groupwiseGeometric(Steps ~ Gender + Teacher,
                   data   = Catbus)

### Example with variable notation                                              
data(Catbus)
groupwiseGeometric(data   = Catbus,
                   var    = "Steps",
                   group  = c("Gender", "Teacher"))
                      

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