mangiaficoD {rcompanion}

Mangiafico's d

Description

Calculates Mangiafico's d, which is the difference in medians divided by the pooled median absolute deviation, with confidence intervals by bootstrap

Usage

mangiaficoD(
  formula = NULL,
  data = NULL,
  x = NULL,
  y = NULL,
  ci = FALSE,
  conf = 0.95,
  type = "perc",
  R = 1000,
  histogram = FALSE,
  reportIncomplete = FALSE,
  verbose = FALSE,
  digits = 3,
  ...
)

Arguments

formula

A formula indicating the response variable and the independent variable. e.g. y ~ group.

data

The data frame to use.

x

If no formula is given, the response variable for one group.

y

The response variable for the other group.

ci

If TRUE, returns confidence intervals by bootstrap. May be slow.

conf

The level for the confidence interval.

type

The type of confidence interval to use. Can be any of "norm", "basic", "perc", or "bca". Passed to boot.ci.

R

The number of replications to use for bootstrap.

histogram

If TRUE, produces a histogram of bootstrapped values.

reportIncomplete

If FALSE (the default), NA will be reported in cases where there are instances of the calculation of the statistic failing during the bootstrap procedure.

verbose

If TRUE, reports the median difference and MAD.

digits

The number of significant digits in the output.

...

Other arguments passed to mad().

Details

Mangiafico's d is an appropriate effect size statistic where Mood's median test, or another test comparing two medians, might be used. Note that the response variable is treated as at least interval.

For normal samples, the result will be somewhat similar to Cohen's d.

The input should include either formula and data; or x, and y. If there are more than two groups, only the first two groups are used.

Currently, the function makes no provisions for NA values in the data. It is recommended that NAs be removed beforehand.

When the data in the first group are greater than in the second group, d is positive. When the data in the second group are greater than in the first group, d is negative.

Be cautious with this interpretation, as R will alphabetize groups in the formula interface if the grouping variable is not already a factor.

When d is close to 0 or close to 1, or with small sample size, the confidence intervals determined by this method may not be reliable, or the procedure may fail.

Value

A single statistic, d. Or a small data frame consisting of d, and the lower and upper confidence limits.

Note

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

Author(s)

Salvatore Mangiafico, [e-mail]

References

https://rcompanion.org/handbook/F_05.html

See Also

multiMangiaficoD

Examples

data(Catbus)
mangiaficoD(Steps ~ Gender, data=Catbus, verbose=TRUE)

Nadja = c(5,5,6,6,6,7,7,11,11,11)
Nandor = c(0,1,2,3,4,5,6,7,8,9,10,11)
mangiaficoD(x = Nadja, y = Nandor, verbose=TRUE)