Effective base (AskiaAnalyse)

This calculation (available on flat and crossed tables) provides the sum of weight factors squared, divided by the sum of the squared weight factors. Effective base is used instead of a weighted base in order to reduce the effect of the weighting, when we want to calculate the Efficiency Test.

The following procedure can be used to check the effective base in Microsoft Excel against the result in AskiaAnalyse.

To check the effective base:

1. After you have created your weighting scheme, create a variable by weighting. In this procedure, we will use an example of calculating the effective base for males who are aged 18-34.
2. In the view menu, select data.
3. Drag your variables into the data window (in our example, we drag across gender, age and weight):
   
4. Copy the data from the data viewer into Microsoft Excel and arrange it as follows:
   
5. Using filters isolate only Males aged 18-34 and copy these into a new tab.
6. Prepare your new tab as follows:
   
7. And apply some simple Excel formulas to work out your effective base:
   
8. You will see that this matches when you check your table in AskiaAnalyse: