Point to Point Wizard: Selection

The first step of the wizard asks for a selection of records to be given.

The records will then be grouped by the geographic variable specified later in the wizard, and each group will have a drive time or distance calculated for it.  

NOTE: If a selection and geographic variable is chosen that will create a lot of groupings, the wizard will take a long time to process the results.

For example, if the selection specified is of the whole FastStats database (containing data on UK addresses) and the geographic variable chosen is Postal Sector, the number of different groupings of postcode sectors in the data could be as much as the total number of postcode sectors in the UK (approximately 12,000).  The wizard would then have to calculate the distance or drivetime from each of these postcode sectors to the centre point, which would take a very long time.

Alternatively, if the selection specified is just of a particular town, a lot fewer postal sectors will be chosen (i.e. in the Holidays example database, there are about 20 postal sectors in Warwick).  Therefore the wizard will be able to process these quickly.

Another approach would be to select all records in the system, but to use a more coarse-grained geographic variable such as Postal Area (of which there are approximately 120 in the UK).  Then in this case the wizard will also be able to proceed quickly.

If a large number of records do need to be processed using a fine-grained geographic variable (such as Postal Sector), the Drive Zone Wizard could be used to place each record into a particular zone (such as between 30 minutes and an hour from the centre point).  Because the records are grouped into zones rather than figures calculated for each record, the wizard is a lot faster.

In this example we will create a selection to identify Households in the West Midlands Region and use it as the Records to Classify, setting the geographic variable as Postal District.

  • Create a Household level selection using the Region variable and select West Midlands

  • Drag the selection onto the Drop your selection here dropbox

Click Next to go to Settings