Very interesting 
http://www.marketingexperiments.com/...headlines.html
Interesting, but their case study is really flawed ...
In all 3 examples, they replaced a "branding headline" with a benefits headline ... if you were to turn each new headline into a question, they would do just as well.
I agree. They changed the entire landers/ads completely, no similarities at all so you can't really say the resulting change in conversion rate is from the question vs no question headline.
Agreed with above. I like questions in my ad copy not in my LP ie Lonely? Get laid here.
^ agree 100%,