Projecting matrix values in the procedure sequence

You can project the maximum values of a square matrix in the procedure sequence. The function is primarily used if you want to multiply origin or destination total values of a zone by a particular value or if you want to reach a particular target value, which e.g. might be necessary after conducting origin-destination study interviews. Matrices collected are often just random samples and must be projected to census values (Fundamentals: Projection).

1.  On the toolbar, click the  Open 'Procedure sequence' window button.

The Procedure sequence window opens.

2.  To the procedure sequence, at the position of your choice, add the Projection of matrices procedure of the Matrices category (Setting up and starting the procedure sequence).

3.  In the row of the newly inserted procedure, in the Reference object(s) column, click the button.

The Select matrix window opens.

4.  Select the desired data matrices that you want to project.

5.  Confirm with OK.

6.  Make sure that the inserted operation is marked and click the Edit button in the Operations section.

The Parameters: Projection of matrices window opens.

7.  Make the desired changes.

Element

Description

Network object reference type

Network object reference of Visum matrices:

  • Matrices with zone dimension
  • Matrices with main zone dimension
  • Matrices with stop area dimension

General parameters

Multiply with factor

Select this option to project the matrix values per row and column, using a factor.

Projection to target value(s)

Select this option to project the matrix values so that their row and column totals approximately correspond to the target values specified.

Projection is executed

From the drop-down list, select the desired reference type for projection:

  • For the entire matrix
  • Singly-constrained production
  • Singly-constrained attraction
  • Doubly-constrained (multi-procedure)

Depending on the selection, the following parameters are available.

Parameter for the reference type "entire matrix"

Factor or Target value

If the projection is executed for the entire matrix, you can enter a factor or a target value.

Parameters for the reference type doubly-constrained (multi-procedure)

Select this option to specify the matrix total used to calculate the multi-procedure if the total of all row sums and the total of all column sums differ due to the factors or target values applied.

  • Production total

The total of all row sums is used as matrix total.

  • Attraction total

The total of all column sums is used as matrix total.

  • Mean of both totals

The mean value of row sums and column sums is used as matrix total.

  • Minimum of both totals

The lower of the two values (total of all row sums and total of all column sums) is used as matrix total.

  • Maximum of both totals

The higher of the two values (total of all row sums and total of all column sums) is used as matrix total.

  • Max. number of iterations

The calculation procedure is canceled as soon as the specified number of iterations is reached.

  • Quality factor

The calculation procedure is canceled as soon as a value falls below a specific limit. The quality factor is included in limit calculation (Fundamentals: Projection).

Note

The higher the quality factor is, the longer the computing time and the higher the precision of the calculations.

Use factors or Use target value

The factors or target values are only relevant for the doubly-constrained (multi-procedure).

Factor for rows from attribute or Target value for rows from attribute

Use the button to select an attribute of the network object selected under Network object reference type that contains the factor or target value for projecting the rows.

Factor for columns from attribute or Target value for rows from attribute

Use the button to select an attribute of the network object selected under Network object reference type that contains the factor or target value for projecting the columns.

Exclude OD pairs between passive objects

This option is only available if the Projection to target value(s) option has been selected.

If this option has been selected, only OD pairs connecting active reference objects are considered.

8.  Confirm with OK.

9.  Execute the procedure (Executing procedures in the procedure sequence).

The values of the selected matrices are projected.