Circadian Quotient and Relative Amplitude from a Cosinor Fit

Computes the circadian quotient (amplitude divided by MESOR) and a cosinor relative amplitude (amplitude divided by the overall mean) from a cosinor result. The circadian quotient is a dimensionless measure of rhythm strength against the rhythm-adjusted mean.

Usage

circadian.quotient(cosinor_result)

Arguments

cosinor_result

A list returned by cosinor.analysis() (class "actiRhythm_cosinor") or any list providing amplitude and mesor. An optional overall_mean (raw arithmetic mean of the counts) is used for the relative-amplitude denominator when present; otherwise mesor is used.

Value

A list with class "actiRhythm_circadian_quotient" containing:

circadian_quotient

amplitude / mesor.

relative_amplitude

amplitude / overall_mean (falls back to amplitude / mesor when overall_mean is absent).

Returns NA entries when the inputs are missing or the denominator is non-positive.

References

Nelson W, Tong YL, Lee JK, Halberg F (1979). “Methods for cosinor-rhythmometry.” Chronobiologia, 6(4), 305–323.

Examples

# \donttest{
ts <- seq(as.POSIXct("2024-01-01", tz = "UTC"), by = 60, length.out = 1440 * 3)
counts <- 100 + 80 * cos(2 * pi * (as.numeric(format(ts, "%H")) - 14) / 24)
cos <- cosinor.analysis(counts, ts)
circadian.quotient(cos)
#> $circadian_quotient
#> [1] 0.8
#> 
#> $relative_amplitude
#> [1] 0.8
#> 
#> attr(,"class")
#> [1] "actiRhythm_circadian_quotient"
# }