Salary, salary regressed on all factors of things (age,sex,years in industry, etc). Once the equation is properly balanced the marginal impact of a PhD is less than the marginal impact of just those added years in the field.

And don’t forget to factor in the opportunity cost of accruing student loan debt (which can’t be defaulted!) against lost yearly income.

Right, but there are outcomes beside salary aren't there?

Pedantically: yes, but almost all of them have salary as a prerequisite.

Practically: no, not really.

My PhD and the research I do now based on it give me a huge amount of personal satisfaction and are a big part of my quality of life. I'm comparing the work I did before my PhD (because I worked after my degree before a PhD) and seeing what my friends think about work compared to me.

Yeah if you're looking for more money, maybe don't do a PhD. If you're looking for the time and space to find satisfaction by working on a unique problem, then it's hard to find something that gives you that in our industry to the same degree.

So that’s the pitch they make in the PhD programs. But what they leave out are the negative associations with a PhD. You will immediately be over qualified for large swaths of work. And unless you can immediately land that dream job by, amongst other things, beating out all competition for that work - you will enter the work force with 0 applicable work experience. Hiring managers can be downright blind about anything that isn’t direct work experience in something you’d only gain experience from already having experience in that labor market.

> And unless you can immediately land that dream job

I'm not sure it has to be immediately, but your point still stands, and it's often ignored by proponents, which is that merely acquiring a graduate degree does not automatically guarantee all those intangible benefits.

One has to actually secure employment with those benefits. Whether that's easier than finding employment with salary benefits instead (or in addition) seems to be still an open question.

Life is short and the basics of survival require daily purchases. So while someone can take a cruddy job while still looking for a better job, all that time does add up to the opportunity cost of going for a PhD. Agree, it’s very much an open question.

Time and space are but a few of the many things that money can buy.