Estimate gravitation parameters

Linear combination of matrices, attribute vectors and/or constants that describes the utility of OD pairs

Insert row in list

Delete marked row from list

If the list contains more than one entry, the + sign indicates that the entries are added row by row.

This button opens the Select operand window, which allows you to select a Visum skim matrix, zone attribute or constant. You can use a function to convert the values of the object selected (Transformation column). You can further multiply them by a factor (Coefficient column).

In the list box, click the function of your choice to convert the values selected in the Matrix / Attribute / Constant column.

In the list box, click the function of your choice to convert the values selected in the Matrix / Attribute / Constant column (Editing matrix values).

If the option has been selected, you can specify intervals for the classes and values for the shares of the classes.

Interval type section

The interval type specifies whether the upper limit or the lower limit of the interval are included in the interval or not.

Note

This option is not available if you import classes and shares via the From interval file option.

[a,b[

If this option has been selected, the lower threshold is included in the interval while the upper threshold is not included.

]a,b]

If this option has been selected, the upper threshold is included in the intervals while the lower threshold is not included.

Lower threshold of the interval

The first interval must have an empty field as From value and an empty field as To value 0. The last interval must have the maximum value as From value and an empty field as To value.

Upper threshold of the interval

The first interval must have an empty field as From value and an empty field as To value 0. The last interval must have the maximum value as From value and an empty field as To value.

Percentage of matrix values that belong to the interval

Note

The share of the intervals with empty fields must be 0.

Percentage of matrix values accumulated from top to bottom

Number of matrix values covered by the interval [Lower limit, Upper limit[

Use this button to add a new interval to the end.

Use this button to delete the selected intervals.

Click this button to delete all existing classes and import new classes and shares from an interval file (*.att) into the list. The setting of the option Interval type is applied to the classes of the import file.

Utility function type for which you want to calibrate the parameters

f(U) = a U^b e^(c U)

Select this option to calculate the parameters a, b and c.

f(U) = a e^(c U)

If this option has been selected, the distribution parameters a and c are calculated, whereas parameter b remains constant = 0.

Select this option to weigh the utility function by the number of trips in each class.

If this option has been selected, matrix balancing by multi-procedure is calculated additionally after the first iteration (Fundamentals: Gravity model calculation).

If you do not select this option, trip distribution is calculated singly constrained for production.

Note

The origin demand (Production) value is regarded for each zone.

Parameters for multi procedure calculation

Note

These options are only available for doubly constrained gravity model calculation.

Maximum number of iterations

After the user-defined number of iterations the internal iteration process is canceled though convergence has not been reached yet.

Quality factor

Criterion for termination of the multi procedure

Store the calculated matrix in matrix

The result matrix calculated during calibration is saved to a Visum matrix. Click the Select output matrix button to select the matrix of your choice (Selecting matrices).

Do not save calculated matrix

The result matrix calculated during calibration is not saved.