MI_index {TestDimorph}

Mixture Index ("MI")

Description

Ipina and Durand's (2010) mixture intersection (MI) measure of sexual dimorphism. This measure is an overlap coefficient where the sum of the frequency of males and the frequency of females equals 1.0. Ipina and Durand (2010) also define a normal intersection (NI) measure which is the overlap coefficient of two normal distributions (each integrating to 1.0), equivalent to Inman and Bradley's (1989) "overlap coefficient." As a result of this rescaling, the "MI" and "NI" plots will appear identical save for the scale on the y-axis.

Usage

MI_index(
  x,
  plot = FALSE,
  Trait = 1,
  B = NULL,
  verbose = FALSE,
  CI = 0.95,
  p.f = 0,
  index_type = "MI",
  rand = TRUE,
  digits = 4
)

Arguments

x

A data frame containing summary statistics.

plot

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

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.

p.f

proportion of sample that is female (if p.f>0 then p.m=1-p.f, where p.m is the proportion of males and bootstrap won't be available) , Default: 0

index_type

type of coefficient (if "MI" it fits the mixture index. If = "NI" it fits the overlap coefficient for two normal distributions, which is equal to 1 – D_index, Default: 'MI'

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

see D_index for bootstrap method.

Value

returns a table of Ipina and Durand's (2010) mixture index ("MI") for different traits with graphical representation.

References

Inman, H. F., & Bradley Jr, E. L. (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.

Ipina, S. L., & Durand, A. I. (2010). Assessment of sexual dimorphism: a critical discussion in a (paleo-) anthropological context. Human Biology, 82(2), 199-220.

Examples

# plot and calculation of MI
MI_index(Cremains_measurements[1, ], plot = TRUE)
#' #NI index
MI_index(Cremains_measurements[1, ], index_type = "NI")
1 - D_index(Cremains_measurements[1, ])$D

## Not run: 
# confidence interval with bootstrapping
MI_index(Cremains_measurements[1, ], rand = FALSE, B = 1000)

## End(Not run)