Typically the values of Pi and Aj are computed based on trip distribution procedures. The values of Fij are computed using
a calibration procedure that involves matching modeled and field trip length distributions. Kij values are used when the
estimated trip interchange must be adjusted to ensure that it agrees with observed trips by attempting to account for
factors other than travel time. The values of K are determined in the calibration process, but considered judiciously when
a zone is considered to possess unique characteristics.