GGIR (version 2.7-1)

g.IVIS: Calculates IV and IS

Description

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)

Value

InterdailyStability

IntradailyVariability

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).

Author

Vincent T van Hees <[e-mail]>

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)