Maybe I'm being blunt, but my definition is that I spoke to them personally and they told me they would still be in academia if they had managed to land a job.

Maybe I'm being blunt, but my definition is that I spoke to them personally and they told me they would still be in academia if they had managed to land a job. I asked, because at the time I was considering leaving to pursue a graduate degree myself. Of course, I didn't literally speak to every quant in on the street, but I sampled from the ones who were around me. Most people were quite open about the situation but glad they had left; some were still very bitter.