That would be very hard to separate. There are very few professors who (in my experience) are professors simply because they want to teach students. The vast ma

That would be very hard to separate. There are very few professors who (in my experience) are professors simply because they want to teach students. The vast majority of them see teaching as simply a requirement to do research. One of the key factors in combining the two is that you are not learning from someone who kind of studied the subject a decade or two previous like you would in high school, you're being taught by someone who is actively research the subject (or a similar subject).