Bodleian Library Map Room - Census 2001 part 3

Back to UK Census pages

UK Census 2001 - creating thematic maps in MapInfo

Census data can be mapped thematically using MapInfo. This guide shows a simple example using the data extracted in the previous step Accessing Census data. For more detailed information on using MapInfo, see the online guide MapInfo - an easy guide for new users

To create a thematic map, you require a boundary map, showing boundaries at the appropriate level (LADs, wards etc.) and a data file with the values to be mapped. MapInfo can create a range of thematic mapping styles and these are covered more fully in MapInfo - an easy guide for new users. For this example, a ranges style map is created, where the individual areas are shaded with colour to show the numeric values.

This example shows how to map the data you extracted from table S101DATAAA3 in the previous section.

The data is at Local Authority District (LAD) level and contains data for every LAD in England and Wales. This means you can map any area within England & Wales. The boundary files available in the Map Room cover Great Britain, so you can simply zoom in on the area you wish to display.

The following basic steps will produce a thematic map showing The total population of each LAD:

1.	Open the table of LAD boundaries (File>Open... select Tables as file type, then open the table: D:\Census 2001\Boundaries\LAD.tab You will see a mapo the LAD boundaries of England & Wales.

2.	Zoom the map out (Right click on the map, then select View Entire Layer from the popup menu).

3.	Zoom in to your area of interest, for example the London area, to display the boroughs.

4.	Open your data file. Assuming you saved this in your user folder, open the file (File>Open and select Delimited ASCII (.txt) as the file type, then open the table). You will see a dialog asking you which delimiter is used. If you have saved it as a Tab-delimited file, then select Tab, if it is comma-delimited then click other* and comma as the type. Click the Use first line for column titles check box as well Click OK to open the table.

5.	You can now create the thematic map. Open the Map menu (if there is no map menu on the menu bar, click the mapper window title bar to make it the active window). Choose Ranges as the map type and choose a style (just choose a range of colours for now - you can change it later). Click Next

6.	In Step 2 of 3, The Table box should show the name of your boundary file (LAD). Click the dropdown arrow next to the Field box and click Join...

7.	In the next dialog (Update Column for Thematic), MapInfo will create a temporary column to hold the census data. The Get Value from Table box should show the name of your data table which is displayed in the Browser window. Click the Join... button.

8.	You will probably see a message telling you that MapInfo cannot automatically compute the join. This doesn't matter - just click OK. You will now see the Specify Join dialog. The problem is that MapInfo is trying to match the name field in the boundary table with the area code in your data table. To fix the problem, simply change the field for the boundary table (in this case LAD) to Code. This matches the GeographyCode field in your data table. Click OK

9.	You are now back at the previous stage, but now you can select a field to map. Choose the total population field and click OK. Click Next...

10.	You are now back to Step 2 of 3, but now you have a field selected, instead of just join... Click Next... and you will see a preview of the legend showing how the data has been grouped. Click OK to display your thematic map!

This guide just covers the basics of creating a thematic map. Full details, including how to modify your maps (colours, ranges, count methods etc.) are in the main mapInfo user guide MapInfo - an easy guide for new users - step 4: data analysis and display - real GIS stuff!

Map Room
Bodleian Library 2003