Multi-resolution Interdaily Stability (IS)

Computes interdaily stability at several within-day bin resolutions. IS is classically reported at 60-min bins, but finer bins (30/15 min) capture higher-frequency day-to-day regularity. For each bin width, IS = (N * sum_h (xbar_h - xbar)^2) / (p * sum_i (x_i - xbar)^2) where p is bins-per-day, xbar_h the mean for bin-of-day h, and N the total number of bins.

Usage

circadian.is.multiscale(
  counts,
  timestamps,
  bin_minutes = (1:60)[1440L%%(1:60) == 0L]
)

Arguments

counts

Numeric vector of epoch-level activity.

timestamps

POSIXct timestamps (one per epoch).

bin_minutes

Integer bin widths in minutes that divide 1440 (default the divisors of 1440 from 1 to 60 min, per Goncalves et al. 2014).

Value

An object of class actiRhythm_ism: a per-bin IS table and the averaged ISm.

References

Witting W, Kwa IH, Eikelenboom P, Mirmiran M, Swaab DF (1990). “Alterations in the circadian rest-activity rhythm in aging and Alzheimer's disease.” Biological Psychiatry, 27(6), 563–572. doi:10.1016/0006-3223(90)90523-5 .

Goncalves BSB, Cavalcanti PRA, Tavares GR, Campos TF, Araujo JF (2014). “Nonparametric methods in actigraphy: an update.” Sleep Science, 7(3), 158–164. doi:10.1016/j.slsci.2014.09.013 .