I emphatically agree with tiffster's comments, btw.
But it seems that the real point of my orginal post didn't make it across. Here's another way I can say it: Have you ever looked at a screenful of 2nd and 3rd degree contacts on LinkedIn and wondered, which of my personal friends connects me to each of these targets? Just as tiffster says, not all introductions are equal. And for that very reason, I find it annoying that LinkedIn won't reveal the introducer's identity (who is one of my personal friends, after all) until I delve specifically into one target's profile.
From that scenario it is one more step to contemplate aggregated reports, which is what I suggested yesterday.