The Estimate gravitation parameters (KALIBRI) function allows you to estimate the distribution parameters a, b and c for a utility function for the gravity model calculation of trip distribution (Calculating trip distribution and Calculating tour-based model - combined trip distribution and mode choice) (Fundamentals: Estimating gravitation parameters (KALIBRI)).
1. Make sure that for each zone, the production and attraction rate per demand stratum are available as zone attributes Productions and Attractions.
2. Each demand stratum for which you want to calculate trip distribution must be allocated to a demand matrix where the results are saved.
3. On the toolbar, click the 
Open 'Procedure sequence' window button.
The Procedure sequence window opens.
4. To the procedure sequence, at the position of your choice, add the Estimate gravitation parameters (KALIBRI) procedure of the Demand model category (Setting up and starting the procedure sequence).
5. In the row of the inserted procedure, click the button in the Reference object(s) column.
The Demand strata selection window opens.
6. Select the desired demand stratum.
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Note: The demand stratum must belong to a 4-stage or tour-based model. |
7. Confirm with OK.
8. Make sure the added procedure is highlighted. Then, in the Operations section, click the Edit button.
The Parameters: Estimate gravitation parameters window opens.
9. Set the desired parameters (Estimate gravitation parameters).
10. Execute the procedure (Executing procedures in the procedure sequence).
The gravitation parameters are estimated.
