Two government economists

Two government economists were returning home from a field meeting. As with all government travelers, they were assigned the cheapest seats on the plane so they each were occupying the center seat on opposite sides of the aisle. They continued their discussion of the knotty problem that had been the subject of their meeting through takeoff and meal service until finally one of the passengers in an aisle seat offered to trade places so they could talk and he could sleep. After switching seats, one economist remarked to the other that it was the first time an economic discussion ever kept anyone awake.