Analysing overlapping catchments

Are you interested in identifying customers located within the intersection of two store catchment areas? Or are you looking to determine the Postcode Sectors that lie within a shared catchment zone? This tip provides instructions on how to create a separate shape of the overlap and pinpoint the Postcode Sectors that exist within this area. However, the same method can be applied to locate customers or various locations by replacing Postcode Sectors with the data points you’re interested in.

You will need to know the Schema name where the shapes are stored and the names of the overlapping shapes.

This is useful if you were analysing communities that are perhaps served by two locations. Knowing these details could help form a strategy to win customers over from competition or help understand demand.

To create the overlap shape:

• Open a map.

• From the left-hand Data tab, select the schema that contains at least one of your catchments

• Right click on this schema and select Add Map Layer | Add Layer

• Click on the Select… button next to Geometry Expression

• Delete the current expression from the Expression box at the top of the window

• In the Expression box type:

INTERSECT(SHAPE_1.'KEY1':MASTER.BOUNDARY, SHAPE_1.'KEY2':MASTER.BOUNDARY)

Where

SHAPE_1 = Schema Name that the shapes are stored in. In this case, SHAPE_1 = Circles and Drivetimes

KEY1 & KEY2 = The names of the overlapping shapes. These can be found by opening a browse on the schema that contains the saved DriveTimes

MASTER.BOUNDARY = Is the geographical boundary column. This does not usually require any change

• Select OK, and then click Next

• Change the properties of the shape as required

• Click Create

• This will add a layer to the map showing the intersect between the two shapes

NOTE: If the layer is not visible, you may need to turn off Show Tagged Only to see the shape

To store the new shape:

• Set the new layer as the Focus Layer

• Click on the shape on the map then select Copy within the Selection Shape section of the Maps tab.

• Select Store – found in the same location

• Give the new shape a Key and a Description

• Change the Schema in which to store your new shape

• Select Ok

The shape will now appear as a row in the schema you saved it to. If there is a browse of this schema open, choose Refresh on the Home ribbon to update the list.