User definitions give you the ability to make a single custom area (or other classifications such as industry, occupation etc.) from several standard ones.

Data from the selections that make up your definition will be aggregated for you and a single figure produced.

Where you need to aggregate data, user definitions can often produce more accurate results than if you were to calculate in your own spreadsheet as the aggregation is carried out on individual figures before any rounding or suppression rules applied.

User definitions are different to saved lists, which are used to save time when you often select a number of areas or industries but still need a figure for each of them.

To create your own user definition (in this example for geography), use the Advanced query:

1. Under geography, choose the user defined option
2. To begin selecting your areas, click the Create your own area link. If you have already selected the areas you want to use in your definition, click the base your definition on current selections link and your current selections will be carried forward to the next step
3. Choose the areas from which your definition is to be made
4. When you are finished choosing areas, click the next > button
5. In the "Enter a name for your area" box, type a suitable name for your definition
6. Click the finish button

You will see your new definition under the "select previously defined area" section of the page. It is automatically ticked, ready for you to use in your query.

Your definition is saved permanently and can be used at any time by selecting it from the "user defined" sub-menu.

To view the contents of your definition or make changes to it, click the edit button next to each name. You will see the list of things that make up this definition and several options to change, rename, delete, make public and copy to another user.

Note that some of these features are available to registered users only and that as a guest your definitions will be lost when you close your browser window.