What are you defining as 'conversion'? Opportunities opened/closed or response rate?
My favorite way to run analytics for campaign conversion is usually to use the revenue cycle analyzer; this gives you insight into where leads are in then entire process based on your campaigns. Have you set this up?
You can use whatever you decided as success in the Program or on a Landing Page.
You should be able to use a Program Performance report.
Kristen, how do I run that report?
Josh - I have been tasked to specifically report the lead conversion rate (tied to opportunities) and I can't find this anywhere.
I should mention we are using spark edition but I do recall when we licensed Marketo last year, being shown a report with conversion rates - opportunities that were created based upon a campaign.
Have you set up your revenue cycle modeler? If you haven't, there are some samples in there from Marketo. I typically set up 2--one for leads and one for customers, so you can see where everyone is by stage. Once you have this set up, you can run reports, directly from the modeler. If you have opportunity as a stage, you can run an analyzer on that particular stage.
Here's the general info/deep dive: https://community.marketo.com/MarketoArticle?id=kA050000000KyvFCAS
Once you approve your model, everyone will fall into a stage and you can run reports. Granted, the best reporting comes from RCA, but I don't believe that's avilable in spark, but if its something your company wants to see, probably worth the upgrade! :)
Hope that helps!