Nope, just a feeling which is further reinforced by other posts on this thread (i.e. confirmation bias) such as:

> Standardized testing was pretty much the only reason I and many other working class folks I know could get into good schools -- I was never going to do a million side activities, and my summers were spent working, not building my academic resume.

– https://news.ycombinator.com/item?id=30833870

> I grew up as a low-income minority in a single-parent household and I ended up getting into good schools pretty much only due to my high test scores, which has been a life changer. Other than test scores, I couldn't afford to do any fancy extra-curriculars.

– https://news.ycombinator.com/item?id=30835611

Of course this is (somewhat) testable. I could ask different collage admission boards to summarize anonymized admission records of students where extra-curricular actives was weighted favorably for admission. And then group these activities based on how accessible they are to various wealth classes before counting them up. I don’t know if that has been done, and I’m not in a position to do it my self... so the best I can do is make a bet.