For the estimation of static origin-destination matrices using traffic counts, Abrahamsson (1998) and other authors propose an objective function that has two components F1 (related to the target matrix) and F2 (related to traffic flows). A factor multiplies each function: γ1 multiplies F1, and γ2 multiplies F2. If the target OD matrix is very reliable, γ1 should be large compared to γ2. I am looking for a mathematical methodology for calculating γ1 and γ2. Is there a methodology for estimating these factors?