Is there any way to group and summarize data entered in a repeating field?

Not really. This is why we don't recommend repeating fields be used for mostly anything. If you wanted to convert to a related file for the data stored in the repeating field, you can go through a multi-step process of exporting and importing the data. This would only be worth the effort if you were going to do in once and elimiate the repeating fields.

-bd

The quick method is to get a found set of the data you want to summarize and import it into another file using the option of splitting the repeating data into individual records. Sort and summarize in this file. You can make a script to do this whenever you need a particular report. This is just a workaround for existing databases where you will only be summarizing fairly small found sets.

The ultimate answer is to convert to related files. If you're setting up a new database, you definitely should be looking at related files.