Looking at Mitre’s phone bills, I knew that only the hacker would call the Army base in Anniston, Alabama. Pretty likely that a phone call made a minute after calling Anniston belonged to the hacker. Same for a call that ended just before dialing Alabama. In physics, this is correlation analysis. If you see a solar flare today and tonight there’s a bright aurora, chances are that these are correlated. You look at things that occur close together in time, and try to find the probability that they’re somehow connected.
