An article summing up a lot of challenges in a scientific career:

http://www.sciencemag.org/content/346/6215/1422.short

…are a curious breed – graduated and passing a heavy selection process but far from having a permanent position or even a chance of obtaining one. Science mentioned some of the common post-doc struggles in its recent article “The stressed-out postdoc“

Science magazine provides the PI-predictor. I don’t know about it’s accuracy, but its an interesting gadget.