Collecting Measures from Summary Tables

Briefly

Select the summary table, then choose Collect Measures from the Analyze menu.

In some situations (especially in simulations) you may want to collect the results of a repeated calculation made on the numbers that appear in a summary table. (It is always possible to write expressions to do this without summary tables, but sometimes summary tables are the most sensible way to think of doing the calculation.)

 

1. Make sure that the quantity you want to collect is calculated in the table, or can be calculated from those quantities.

2. Select the summary table.

3. Choose Collect Measures from the Analyze menu. A new collection appears.

This new collection has one case for each cell in the summary table. Its attributes and values are the quantities that were calculated in each cell. As this is the same information that was in the table, this is not useful on its own. So we proceed…

4. Define a measure in this new, Measures collection where you calculate a statistic of interest. (Often this is something, like chi-square, which you calculate from the cell counts.)

5. Be sure this Measures collection is selected.

6. Again choose Collect Measures from the Analyze menu. Another new collection appears, named Measures from Measures from <your collection name>.

If the original data has some random part to its definition, this final collection will contain a distribution of the statistic you defined as the original collection varies randomly.