Calculates IV and IS — g.IVIS • GGIR

To extract interdaily stability and interdaily variability as originally proposed by van Someren.

Usage

g.IVIS(Xi, epochsizesecondsXi = 5, IVIS_epochsize_seconds = c(),
    IVIS_windowsize_minutes = 60, IVIS.activity.metric = 1,
    IVIS_acc_threshold = 20, IVIS_per_daypair = FALSE)

Arguments

Xi: Vector with acceleration values, e.g. ENMO metric.
epochsizesecondsXi: Epoch size of the values in Xi expressed in seconds.
IVIS_epochsize_seconds: This argument has been depricated.
IVIS_windowsize_minutes: Window size of the Intradaily Variability (IV) and Interdaily Stability (IS) metrics in minutes, needs to be able to add up to 24 hours.
IVIS.activity.metric: Metric used for activity calculation. Value = 1, uses continuous scaled acceleration. Value = 2, tries to collapse acceleration into a binary score of rest versus active to try to simulate the original approach.
IVIS_acc_threshold: Acceleration threshold to distinguish inactive from active
IVIS_per_daypair: Boolean to indicate whether IVIS should be calculated per day pair and then aggregated across day pairs weighted by day completeness (default FALSE).

Value

InterdailyStability
IntradailyVariability

Author

Vincent T van Hees <v.vanhees@accelting.com>

References

Eus J. W. Van Someren, Dick F. Swaab, Christopher C. Colenda, Wayne Cohen, W. Vaughn McCall & Peter B. Rosenquist. Bright Light Therapy: Improved Sensitivity to Its Effects on Rest-Activity Rhythms in Alzheimer Patients by Application of Nonparametric Methods Chronobiology International. 1999. Volume 16, issue 4.

Examples

  Xi = abs(rnorm(n = 10000,mean = 0.2))
  IVISvariables = g.IVIS(Xi=Xi)