Research: The Cost of a Queue

Learn how the length of the queue impacts a customer's purchasing behavior.

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It may surprise some frustrated shoppers waiting on a long line that much thought has been put into the design of a store to manage such waits. “Queueing theory” has been a topic of study for over a century, however most research has focused on balancing operating costs against the level of service offered to the customers. Until now, there has been little work done to identify how the length of a line affects a customer’s purchasing behavior.

Columbia professor Marcelo Olivares and Columbia doctoral candidate Yina Lu, along with Duke professor Andres Musalem and Scopix Solutions’ Ariel Schilkrut, examined how the length of a line impacts purchase decisions. Combining novel digital imaging technology and customer transaction data, they created models that quantify the effects of queues on purchase incidence, switching behavior and sales.  For a queue length of 15 customers or more, purchase incidence reduces from 30% to 27%, corresponding to a 10% drop in sales.

The researchers also found that it is the queue length and not the anticipated waiting time that affects customer behavior. In addition, they discovered that waiting is negatively correlated with price sensitivity.

Read more from Columbia’s Ideas at Work research summary, which includes a link to the full paper.

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