I'm trying to calculate the ROI (return on investment) of my network. We have adds from Facebook, Adwords, Taboola and Outbrain that goes to a wordpress site. Then, there is a button that goes to our Landings engine that is where the client buy our products.
There is a success page but it is from the landings engine.
A kind of graphic was: advertisement -> wp -> landing (with form) -> landing success.
In analytics I want to see in Acquisition -> AdWords -> campaigns, the ROI.
There's really only a couple of ways to do this that I can see:
1 If you have access to the template code for the external form and success pages you can add your analytics code snippet with your ID, and then use a ga() call to send a pageview for those urls. If the form is an ajax form that doesn't reload the page on success...you'll need to be able to tie into some sort of "onsuccess" handler to send the ga() call with a virtual pageview...something like '/external-form/thankyou/' or whatever.
2 If you don't have access to the form code, but the form allows you to re-direct on success...re-direct them to a "thank you" page on your own site.
Then...in Google Analytics, setup a goal conversion based on a "destination url."