In my department, students make about $40K/year as a base salary, which is not a lot, but enough to get by with. Add a summer internship to this, and your income is not too shabby--I made about $70K this year.
Now, of course, I realize this is half or less of what students would be making in industry. But it's enough that quality of life is pretty decent.
Erm. It's the median personal income and more than like 61% of the country's population makes. More than I make after 12 years on the job.
But below median for a college graduate, much less one with an undergraduate degree in CS or another high-demand technical field, and way below median (and quite possibly poverty level) for some of the local areas where big-name CS graduate programs are located.
Students in my program usually end up paying 40-60% of the base salary toward rent.
That's incredibly high as a base rate! Most departments I know pay between $28k and $32k. The only people I know at $40k have an NSF fellowship.
For France and Germany, stipend/wages range roughly from 1200€ to 1800€/mont, so a bit over minimal wage, and definitely under what you could do in the private sector.
A full-time position pays around 44.000€/year (varying a bit from state to state) which is ~3.650€/month. This goes up over time, up to around 56.500€/year. All of this is public information, TV-L 13 is the keyword to look for (TV-L stands for "Tarifvertrag der Länder", 13 is the group in which PhD students are typically placed by universities). Source in German: http://oeffentlicher-dienst.info/tv-l/west/ Table for salary per month in Euro (relevant row is E 13): http://oeffentlicher-dienst.info/c/t/rechner/tv-l/west?id=tv...
If you don't get a full-time position, you get proportionally less, obviously. In theory if you only have a 50% position and only get 1.800€/month, you should be able to work somewhere else to make up for it. In reality, though, this isn't happening as the professors are tricking the system and are practically abusing the PhD students' dependency on the professor's good-will as he/she is the one who is deciding whether they graduate or not. So even even if a PhD student is only being paid for 20 hours of work a week (50%), they are still expected to work 40h or more.
In non-STEM fields this is sadly happening all the time, sometimes to the extreme where 4 (or even more!) PhD students are being paid from the budget for a single full-time position. In Computer Science, however, I didn't meet a single PhD student that wasn't employed full-time.
Also, that's not so much under what you would do in the private sector. In 'industry', you don't so often start over 1800€/month with a master, even less so in humanities. I mean, it is not rare to start with more, but something like half of people will get less, and the other half won't get much more.
PhD students definitely earn >=2k1 here.
In Portugal you get a fellowship that covers tuition and a monthly stipend which was increased for the first time in 15 years (by 1.4%) last year. PhD fellows are not considered employees of the University and since the stipend is not really a salary you are stuck in a weird financial situation.
Despite all this, it is enough to live (around 1000 Eur) in most of the country except for the capital (due to house/rent prices have been increasing for the past 2 years at galloping rate), which is where a great number PhD granting institutions are located.
Not to pile up, I've also discovered that you can be granted a PhD fellowship for a project at an host institution that is under equipped (if has any equipment at all) for that project.
In terms of adding value, I guess it depends on both the field and what your objectives are. For example, I work in a field where no one would offer you a job unless you have PhD or some sort insane amount of experience.
From my experience, IT companies only differentiate CS, electric engineers and computer engineers for entry/junior level it jobs from the rest of the engineering and scientist. Biochemists, civil engineers, physicists, chemical engineers, industrial engineers, etc. Are all the same for the HR and assume you have 0 coding skills.
Keep in mind that this is not necessarily true for schools in countries outside of the US. At my school, KTH Royal Institute of Technology in Stockholm, as a PhD student you are considered an employee of the school and you are paid a living wage with full benefits. The current salary starts at 28600 SEK/month and can reach up to 33500 SEK/month [1] which is definitely a living wage in Stockholm, especially considering that you can live in affordable student accommodation (as long as you have been on the waiting list for at least a year or so for a student dorm). Sure, you can definitely make more money working in the industry, but at least you will not be living in poverty while pursuing your PhD degree.
As far as I know the public schools in Norway and Denmark operate very similarly to this, but I am not sure about other schools in Europe.
[1] https://www.kth.se/en/studies/phd/student/employment-1.52704...