This improvement seems crazy, but it's actually fairly easy to explain.
The campaigns I had run throughout the month had some winners hidden in them. They were all ROI negative, but I had plenty of conversions and data to sort through.
As I was analyzing my campaigns, I realized that there was a set of sources that were converting for a particular offer in a particular vertical.
I setup 5 new offers in Voluum to split test against the original offer and focused on just the sources that were converting.
Sure enough, 2 of the offers outperformed the original offer by over 100%. On top of that, because I am only focused on a few sources, I am not wasting my daily budget on sources that don't seem to convert for this particular vertical.
It's not rocket science, but it takes time. Collect your data, optimize (you don't have to wait all month like I did), and test some more!
I am not sure if this campaign will be a long term winner, but for now, it's performing well and I should be able to maintain a positive ROI for awhile :)
Thanks,
Luke