I'm not sure this would be very useful if you're only looking at people who successfully got a job in that field. Let's assume software devs make the comparable

I'm not sure this would be very useful if you're only looking at people who successfully got a job in that field. Let's assume software devs make the comparable salaries regardless of education. It could still be true[0] that CS degree holders who look for tech jobs get one 80% of the time, whereas non-degree holders who apply for a tech job get one 20% of the time and end up in a much lower-paying job. The analysis you suggest would indicate a college degree has no effect on salary, but it actually had a huge effect if you consider everyone who was interested in tech but didn't make it. [0] and in my opinion very likely, aside from these specific percents being made up and probably pretty far off.