Test whether groups share the same concentration (dispersion)

Two tests are available:

parametric = TRUE (default)

Likelihood-ratio test for equal von Mises \(\kappa\) across groups (equal.kappa.test). Returns a chi-squared statistic with \(k-1\) degrees of freedom.

parametric = FALSE

Wallraff's non-parametric test for equal angular dispersions – no distributional assumption required.

Usage

test_concentration(
  hd,
  group_col,
  angle_col = "heading",
  parametric = TRUE,
  axial = FALSE
)

Arguments

hd

Data frame with heading and group columns.

group_col

Column identifying conditions or groups.

angle_col

Heading column in radians. Default "heading".

parametric

Logical. TRUE (default) uses equal.kappa.test; FALSE uses wallraff.test.

axial

Logical. Treat the angles as axial (bidirectional, mod-pi) data: the test is run via the angle-doubling method, comparing axial concentrations. Default `FALSE` (ordinary directional data).

Value

One-row tidy data frame with statistic, df (parametric only), p_value, and test.