accelerometry (version 2.2.3)

accel.intensities: Classification of Physical Activity Intensities

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, ... ,

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.

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)