Scientifically, You Probably Are in the Slowest Moving Line
The video was released just in time for the final days of the holiday shopping season, as a lesson in queueing theory for the holiday season. Using the work of Agner Erlang, a Danish engineer who helped the Copenhagen Telephone Company determine the best level of service with the minimum number of operators, Hammack shows stores can determine the best number of cashiers in a store.
Ironically, the most efficient set-up is to have one line feed into several cashiers. This is because if any one line slows because of an issue, the entry queue continues to have customers reach check-out optimally. However, this is also perceived by customers as the least efficient, psychologically.
In fact, scientifically, it can be proven that the other line is more likely to move faster than your line. As shown in the video, in a system with three checkout lines, 2/3 of the time, the other lines will move faster than yours. Watch the video below.