accel_intensities: Classification of Physical Activity Intensities

In accelerometry: Functions for Processing Minute-to-Minute Accelerometer Data

Description

This function computes the number of minutes with counts in user-defined intensity levels, and the number of counts accumulated during time spent in each intensity level. It is intended for use with minute-to-minute accelerometer data.

Usage

accel.intensities(counts, thresh = c(100, 760, 2020, 5999), skipchecks = FALSE)

Arguments

counts	Time series accelerometer counts vector.
thresh	Vector of four cut-points from which five intensity ranges are derived. For example, if thresh = c(100, 760, 2020, 5999), minutes with 0-99 counts are classified as intensity level 1, minutes with 100-759 counts are classified as intensity level 2, ... , and minuts with 5999 or greater counts are classified as intensity level 5. By default the function also returns time in intensities 2-3, 4-5, and 2-5.
skipchecks	If TRUE, function skips error checking code and runs slightly faster.

Value

An integer vector in which the first eight values are minutes in intensity 1, 2, 3, 4, 5, 2-3, 4-5, and 2-5, respectively, and the next eight values are counts accumulated during time spent in intensity 1, 2, 3, 4, 5, 2-3, 4-5, and 2-5. Intensities 1-5 typically correspond to sedentary, light, lifestyle, moderate, and vigorous.

Note

Users should generally input a vector of counts that occur during wear time only. Otherwise the estimate for intensity range 1 (sedentary) will include non-wear time and be vastly overestimated.

Some additional information on the package accelerometry and its functions can be found on the author's website, https://sites.google.com/site/danevandomelen/

Author(s)

Dane R. Van Domelen

References

Acknowledgment: This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-0940903.

See Also

accel.weartime, accel.process.uni, accel.process.tri

Examples

# Load in sample data frame
data(unidata)

# Get data from ID number 21005
counts.part1 <- unidata[unidata[, "seqn"] == 21005, "paxinten"]

# Create vector of counts during valid wear time only
counts.part1.weartime <- counts.part1[accel.weartime(counts = counts.part1) == 1]

# Calculate physical activity intensity variables
intensity.variables <- accel.intensities(counts = counts.part1.weartime)

accelerometry documentation built on May 2, 2019, 5:23 p.m.