Phase Concentration Tests

Tests whether a set of daily phase markers (acrophases, onsets, L5/M10 times) are concentrated rather than scattered around the clock. Reports the mean resultant vector, the Rayleigh test of uniformity (Fisher 1993), and the Hermans-Rasson test (Landler et al. 2019), which catches multimodal clustering that Rayleigh misses.

Usage

phase.concentration(times_h, period = 24, n_perm = 2000)

Arguments

times_h

Numeric vector of clock times (hours, 0-24), one per day.

period

Period the times wrap on, in hours (default 24).

n_perm

Permutations for the Hermans-Rasson p-value (default 2000, a speed tradeoff; Landler et al. 2019 use 9999 for a finer minimum p-value).

Value

An object of class actiRhythm_phasetest: mean direction, mean resultant length R, and the Rayleigh and Hermans-Rasson statistics and p-values. Never errors.

References

Fisher NI (1993). Statistical Analysis of Circular Data. Cambridge University Press. doi:10.1017/CBO9780511564345 .

Landler L, Ruxton GD, Malkemper EP (2019). “The Hermans-Rasson test as a powerful alternative to the Rayleigh test for circular statistics in biology.” BMC Ecology, 19, 30. doi:10.1186/s12898-019-0246-8 .

Examples

set.seed(1)
onsets <- 23 + stats::rnorm(10, 0, 0.5)      # tightly clustered near 23:00
phase.concentration(onsets %% 24)
#> Phase Concentration Tests
#> 
#>   n days:          10
#>   Mean direction:  23.07 h    R: 0.995
#>   Rayleigh:        Z = 9.91, p = 0.0000
#>   Hermans-Rasson:  V = 27.22, p = 0.0005
#>