Waiting Time

Waiting time is the time between an expectation for service and the beginning of the service delivery. It occurs when a request for service cannot be satisfied immediately due to a server being occupied with other requests or due to a server being temporarily out of service. Waiting (or queuing) occurs in most service operations and is primarily due to the variation in customer arrivals and service times. Customers arriving for service can be either scheduled appointments or unscheduled walk-ins. Arrivals for scheduled appointments may exhibit variation around their appointment times; however, such variation can often be reduced by reminder calls, communication, or late penalties. Walk-in customers generally arrive according to a Poisson process and are characterized by extremely high levels of variation in interarrival times.

As an example of the effects of random (Poisson) arrivals, suppose the time between patients arriving to a one-physician walk-in clinic averages 15 minutes. If the time to treat each patient were exactly 12 minutes, it would seem there would be no waiting, because the rate of arrivals is less than the rate of service. With the arrival process being random, however, the result is that the average patient wait before being treated will be 24 minutes.

If there also exists variation in the time it takes to provide a service, the waiting time can increase substantially. Continuing with the example, suppose the treatment time averages 12 minutes but exhibits considerable variation (such variation is sometimes modeled using an exponential distribution). In this example, the combined effects of the random arrivals and the random treatment times would increase the average waiting time to 48 minutes.

Within health care, waiting time is often cited as the most common reason for patient dissatisfaction. Even with considerable efforts in variation reduction, some degree of waiting is inevitable in health care systems. As such, careful attention should be given to the waiting environment and to managing the customer's perceptions of the wait. Several practices have been shown to be effective in combating negative perceptions of wait.

The waiting environment should be designed to keep a waiting customer comfortable and occupied. Standard techniques for keeping a waiting customer occupied include magazines, television, and informational brochures. More recently, such techniques include free phone and Internet access, as well as computer-based games and information services. Staff should be in constant communication with customers regarding a waiting situation, beginning with a simple acknowledgment that the customer is in the system (“We'll let the doctor know you're here”). In cases where a wait may be long, customers should be advised and updated of the likely or worst-case wait and the reasons for the wait (“Dr. Smith had an emergency delivery this morning, and so we are running about an hour late”). It is also important to maintain fairness in waiting situations or to explain situations that could be perceived as unfair. For example, many emergency departments make it clear that life-threatening cases will be taken ahead of minor injuries. It's important to recognize that many waiting situations in health care are anxiety filled and warrant special attention. For example, a patient awaiting test results may wrongly interpret a growing wait as an increasing probability of “bad news.” In such situations, it may be important to communicate a “no news” status in the event of delayed results.

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