Output Variables

Updated: 30 May 2012

This section describes the outputs of the PALMS system. PALMS calculations produce result sets which can be used in other calculation or exported as CSV files for use by other programs. In addition, results sets can be converted into KML files for viewing within Google Earth and other mapping programs.

PALMS Calculation Output Variables

The PALMS calculation processes the GPS data to detect trips and locations. It merges accelerometer and heart rate data (if available) by synchronizing the timestamps. From the merged datasets, it estimates mode of travel, detects bouts for physical activity and sedentary behavior, and estimates energy expenditure.

The resulting dataset is exported by participant id, by date, by interval running from midnight (00:00:00) to midnight (23:59:59). Intervals are typically 5, 10, 15, 20, 30, 60 seconds.

Additional Variables available in Release R4
The following changes have been made in the output of Release R4 of the PALMS calculation:
  • GPS
    • Information previously encoded as strings in the fixType column now appears as integers in individual columns: fixTypeCode, iov, tripType, tripMOT, locationClusterFlag.
    • fixType column is kept for backwards compatibility
    • In-vehicle mode added to indoor / outdoor estimation
    • Speed changed from integer to decimal
    • Additional GPS columns have been added: pdop, hdop, vdop
  • Accelerometer
    • Columns for all three axis and vector magnitude (if available)
    • Column for step count (if available)
    • Sedentary bouts moved to separate column
  • For ActiGraph devices
    • Columns for lux, lux intensity and incline
  • Heart Rate Processing
    • Add invalid value (indicates device as not worn)
    • Individual columns for raw and filtered heart rate
  • Events (event number and event type)
  • Day of Week column added

Release 2 and 3 Output Variables:
Release 4 Output Variables:

Daily Summary.csv
The daily summary output groups the output of the main calculation into periods of activity. A period is defined in a change in the participant’s location (trip), physical activity level (bout) or sedentary behavior.

Each period has a starting and ending time, a starting and ending location, period classification (or mode of transportation when moving), and the accumulated time spent at various levels of activity during that period.

Midpoints of a trip (the path of a trip) are not exported, thus it is not possible to used this file to analyze the path of travel. Pause points (momentary stops within a trip) are exported. Changes in mode of transportation (i.e.: from walking to vehicle) within a trip are exported.

The data is exported by participant id, by day, by period running from midnight (00:00:00) to midnight (23:59:59).

Additional details can be found in this document: