Try the Topic Properties Report. That shows the Status and To Do's marked against a topic, the two have no connection. That report can be saved as a text file and from there you should be able to get the information into a spreadsheet for analysis.
See www.grainge.org for RoboHelp and Authoring tips
Peter, as always, you have an excellent suggestion.
I did as you said, running the Topic Properties Report. I modified the options for the report (Options button) so that the only thing selected is Completed To Do's under Topic Status. I opened that in Excel and now I have something that, although not formatted very well, is something I can work with. (I'll have to study up on how to filter things in Excel.)
I also put in a request for enhancement to Adobe. I'd like to be able to drag a To Do tag onto the regular Topic List view so that I can see all the topics that have a certain status. Having seen the Excel version, though, I'm now wondering if I should instead ask for a .CSV version.
For anyone else who's interested, here's what to do, step by step.
1. Navigate to Tools > Reports > Topic Properties.
2. Click the Options button.
3. On the Topic Report Options screen, clear all checkboxes except Completed To Do's.
4. Click OK.
5. When the report finishes, click Save As. Save the report as a text file (.txt).
6. Start Excel.
7. Use File > Open to open the .txt file from within Excel.
8. When the Text Import Wizard opens, click Finish without changing the default.