The CF-Index, or Conference Frustration index, is an integer n (n ≥ 1) defined as follows. You are at a conference where your paper submission was rejected, and sitting in the session devoted to that paper’s very topic. You think for yourself “My paper was at least n times better than the average here”. That n is your CF-index.
It is a law of nature (like speed never exceeding that of light, or temperature never going below absolute zero) that n < 1 is impossible. (The reason is obvious: if you were not the kind to believe your work is at least as good as anyone else’s, you would have gone for another profession, one calling for modesty, realism and timidity — such as, say, politician.) Values of n = 3 or 4 are normal. Beyond 10 you might consider seeking professional advice. (These observations have nothing to do with my being at ICSE right now.)