Evaluating potential supervisors on the basis of past graduate student results I am lucky CS senior undergrad who has received offers from a number of good departments in the USA. I am currently going through the usual factors for evaluating departments and supervisors. In the process, I've noticed a common trend in advice: most of the advice that I've gotten has not mentioned looking at where most of the students end up (e.g. quality of the thesis, do they get post-docs, coding jobs, industry research jobs, etc). Most advice (that I have read) emphasizes, not unproductively, the adviser-student relationship and the supervisor's research interests. This observation has led me to several questions:


Is it appropriate to ask potential supervisors what most of their students end up doing and why? Is there some other way to talk about this with potential supervisors?
How much should this factor into one's decision? Obviously, a lot of what happens to me is up to me and luck, but also obviously my supervisor plays some role in this beyond helping directly with my research.
Is there an easy way to figure out this information? Anything better than googling lots of names?
Are there more qualitative ways of looking at this question besides just looking at bare results? (Given the relative scarcity of positions over time and the amount of luck involved, I am amenable to the argument that simple stats are useless here.)
It's perfectly acceptable to ask a supervisor what their former students are doing now, and I think the majority of supervisors would be more than happy to discuss it. They might even give you email addresses of their old students -- I myself have been contacted many times by prospective students of my supervisor and am always happy to answer their questions. 

How much you factor the information you gain into your decision is really up to you, and depends a lot on your own motivations for doing a PhD and what you want to get out of it. For example, if you want to go into industry afterwards but a supervisor tells you that all of her former students are still in academia, would that influence you away from studying under her? Or if the majority of a supervisor's students are now in industry, how do you know whether they had to leave academia because they couldn't get a postdoc or because they really wanted an industry job instead?