TestDimorph (version 0.5.8)

D_index: Dissimilarity index

Description

Visual and statistical computation of the area of non-overlap in the trait distribution between two sex groups.

Usage

D_index(
  x,
  plot = FALSE,
  fill = "female",
  Trait = 1,
  B = NULL,
  verbose = FALSE,
  CI = 0.95,
  rand = TRUE,
  digits = 4
)

Value

a table and a graphical representation of the selected traits and their corresponding dissimilarity indices, confidence intervals and significance tests.

Arguments

x

A data frame containing summary statistics.

plot

logical; if TRUE a plot of densities for both sexes is returned, Default: FALSE

fill

Specify which sex's density to be filled with color in the plot; either "male" in blue color, "female" in pink color or "both", Default: 'female'

Trait

Number of the column containing names of measured parameters, Default: 1

B

number of bootstrap samples for generating confidence intervals. Higher number means greater accuracy but slower execution. If NULL bootstrap confidence intervals are not produced, Default:NULL

verbose

logical; if TRUE number of bootstraps is displayed, Default: FALSE

CI

confidence interval coverage takes value from 0 to 1, Default: 0.95.

rand

logical; if TRUE, uses random seed. If FALSE, then set.seed(42) for repeatability, Default: TRUE

digits

Number of significant digits, Default: 4

Details

Chakraborty and Majumder's (1982) D index. The calculations are done using Inman and Bradley's (1989) equations, and the relationship that D = 1 - OVL where OVL is the overlap coefficient described in Inman and Bradley. A parametric bootstrap was used assuming normal distributions. The method is known as the "bias-corrected percentile method" (Efron, 1981) or the "bias-corrected percentile interval" (Tibshirani, 1984)

References

Chakraborty, Ranajit, and Partha P. Majumder.(1982) "On Bennett's measure of sex dimorphism." American Journal of Physical Anthropology 59.3 : 295-298.

Inman, Henry F., and Edwin L. Bradley Jr.(1989) "The overlapping coefficient as a measure of agreement between probability distributions and point estimation of the overlap of two normal densities." Communications in Statistics-Theory and Methods 18.10:3851-3874.

Efron, B. (1981). Nonparametric standard errors and confidence intervals. Canadian Journal of Statistics, 9(2), 139-158.

Tibshirani, R. J. (1984). Bootstrap confidence intervals. Technical Report No. 3, Laboratory for Computational Statistics, Department of Statistics, Stanford University.

Examples

# plot and calculation of D
run.D <- function() {
  print(D_index(Cremains_measurements[1, ], plot = TRUE))
  cat("Published D value: ", Cremains_measurements[1, 8], "\n")
}
run.D()

if (FALSE) {
# confidence interval with bootstrapping
D_index(Cremains_measurements[1, ], rand = FALSE, B = 1000)
}