Originally Posted by ethernal

Sure, if by random you mean not random. There is indeed some true random selection, but the majority of the selections are pre-determined based on an arbitrary risk algorithm. While just one of many variables considered, ask any traveler who has spent time in Afghanistan, Syria, Yemen, or other countries the DHS deems as high risk how much more they seem to be "randomly" selected than before. The small number of true random selections is so that the DHS can pretend it is random rather than abusive and discriminatory.