Sensor measurement accuracy and precision.

The rows corresponding to the smartphone GPS provide the accuracy (central error, CE [2]) and precision (standard deviation, SD) of the GPS-derived position relative to simultaneously collected DGPS position of the moving pair of sensors (see the following section for our definitions of these statistics). The smartphone accelerometer rows provide a measure of precision of the sensor’s body fixed acceleration when the smartphone is motionless. Similarly, the differential GPS rows provide a measure of precision of the motionless rower position relative to the motionless base station. The duration of the data logs used to derive these metrics and the frequency at which they were sampled are listed for each sensor.