Hi :)
I used Google Analytics and I constantly tracked all the activity on the Facebook page and groups, comparing the performance of each text in many ways. I also talked to a lot of people about the texts and what perception they had of the EA movement so far. Apart from that, I frequently offered my contact information, and we have a Facebook group for EA in Spanish in which interested people could ask questions(almost all of them were either about effective animal activism or off-topic).
These methods allowed me to get a very good general idea. We could have done more things to track changes, but we had a small team team and limited time, so we focused on the main things.
If I ever start this project again working full time and with a strong team, I will definitely look for the most precise ways to track impact.
It’s a shame that you think that EA isn’t for you. We could use more people like you.
Please remember that I don’t represent the whole movement. If you can and you are interested, It would be nice if you could look what other EAs have to say. You may like it a lot more.