Impact of Queue Configuration on Service Time: Evidence from a Supermarket

We study how queue configuration affects human servers’ service time by comparing dedicated queues with shared queues using field data from a natural experiment in a supermarket. We hypothesize that queue configuration may affect servers’ service rate through several mechanisms: pooling may affect service rate directly as a result of social loafing effect and competition effect and indirectly via its impact on queue length. To investigate these impacts, we take advantage of the supermarket’s checkout layout and use a data set containing both checkout transaction details and queue information collected from video recordings in the supermarket. After we control for the queue length, we find that servers in dedicated queues are about 10.7% faster than those in shared queues, mainly because of the social loafing effect. We also demonstrate that pooling has an indirect negative effect on service time through its impact on queue length. In addition, the queue configuration’s direct effect and its indirect queue length effect function independently of each other. In aggregation, the social loafing effect dominates, and servers slow down (a 6.86% increase in service time) in shared queues.

This paper was accepted by Serguei Netessine, operations management.