Queuing Theory and
Customer Satisfaction: A Review
of Terminology, Trends, and
Applications to Pharmacy Practice
Ronald Anthony Nosek, Jr., MS* and James P. Wilson, PharmD, PhD†W
aiting in lines or “queues” seems to be an American pastime. Think about the many times you had to wait in line in the lastmonth or year and the time and frustra-tion that was associated with those waits. Whether we are in line at the gro-cery store checkout, the barbershop, the stoplight, or in the pharmacy, “waiting
our turn” is part of our everyday life. Queuing theory is the formal study of waiting in line and is an entire disci-pline within the field of operations management. The purpose of this arti-cle is to give the reader a general back-ground into queuing theory and queu-ing systems, its associated terminology, and how queuing theory relates to cus-tomer satisfaction. Also, past and pre-sent applications of queuing technology and what pharmacies can do to manage patient or customer queues more effec-tively will be discussed. Finally, auto-mated queuing technology will be described.
Queuing theory utilizes mathemat-ical models and performance measures to assess and hopefully improve the flow of customers through a queuing system.1–3 Queuing theory has many
applications and has been used exten-sively by the service industries. Queu-ing theory has been used in the past to assess such things as staff schedules, working environment, productivity, customer waiting time, and customer waiting environment. In pharmacy, queuing theory can be applied to assess a multitude of factors such as prescrip-tion fill-time, patient waiting time, patient counseling time, and pharmacist and technician staffing levels. The application of queuing theory may be of particular benefit in pharmacies with high-volume outpatient workloads and/or those that provide multiple points of service, such as those in the
Abstract — Queuing theory is the formal study of waiting in line and is an entire discipline in operations management. This article will give the reader a general background into queuing theory, its associated terminology, and it relationship to customer satisfaction. Queuing theory has been used in the past to assess such things as staff schedules, working environment, productivity, customer waiting time, and customer waiting environment. In pharmacy, queu-ing theory can be used to assess a multitude of factors such as prescription fill-time, patient waiting fill-time, patient counseling-fill-time, and staffing levels. The application of queuing theory may be of particular benefit in pharmacies with high-volume outpatient workloads and/or those that provide multiple points of service. By better understanding queuing theory, service managers can make decisions that increase the satisfaction of all relevant groups — customers, employees, and management.
Key Words — customer satisfaction; queuing
Hosp Pharm —2001;36:275–279
*Pharmacy Department, The National Naval Medical Center, Bethesda, Maryland, 20889; [email protected] (Ronald A. Nosek, Jr., LCDR, MSC, USN is an active duty pharma-cist in the United States Navy. At the time of writing this article he was attending the University of Texas as a full time student in Navy’s Duty Under Instruction program); †Assistant Professor, Pharma-cy Practice and Administration Division, The University of Texas College of PharmaPharma-cy, Austin, TX; [email protected]. Address correspondence to Dr. James P. Wilson, Pharmacy Practice and Administration Division, PHR 2.212 – Mail Code A1930, Austin, TX 78712; [email protected].
Department of Veterans Affairs (VA), Department of Defense (DoD), univer-sity health systems, and managed care organizations. Problematic queuing systems (ie, long lines) can lead to the customer’s perceptions of excessive, unfair, or unexplained waiting time— resulting in significant detrimental effects on the customer’s overall satis-faction with the service transaction.4
QUEUING SYSTEMS AND TERMINOLOGY
On the surface it may seem like queuing is just simply waiting in a line. To most customers, the waiting experi-ence is all that matters. However, wait-ing in line is just a part of the overall queuing system. A queuing system (also known as a processing system) can be characterized by four main ele-ments: the arrival, the queue discipline, the service mechanism, and the cost structure.
The arrival is the way in which a customer arrives and enters the system for service. Whenever customers arrive at a rate that exceeds the processing system rate, a line or queue will form. Arrivals may come in singly or in batches; they may come in consistently spaced or in a completely random man-ner. A potential customer can also leave if, on arrival, he or she finds the line too long—this is called balking.
The queue disciplineis the rule for determining the formation of the line or queue and the order in which jobs are processed. There may only be one line and jobs are processed In, First-Out or FIFO. Others may have more than one line to give certain customers priority such as express lanes in grocery stores.
The service mechanism describes how the customer is served. It includes the number of servers and the duration of the service time—both of which may vary greatly and in a random fashion. The service time may be similar for each job or it could vary greatly.
The cost structure specifies the
payment made by the customer and the various operating costs of the system. Other elements that impact the queue structure and performance include the number of service stations and the number and speed of servers.2,5
THE IMPORTANCE OF QUEUING MANAGEMENT
Pharmacy, like other service-ori-ented industries, functions in an increasingly competitive environment. Speed of service has been shown to provide businesses a competitive advantage in the marketplace.4In
addi-tion, the literature reveals several stud-ies documenting customer dissatisfac-tion with long waiting times and indi-cates that this is a pervasive problem in pharmacy practice and a common source of anxiety and dissatisfaction among customers and, in many cases, pharmacists.6
Speed of delivery is being empha-sized increasingly and can be partly attributed to increased competition and the value a customer places on his or her time. We live in a society who has come to expect film development and eyeglasses to be ready in an hour or less. A brief story told from the cus-tomer’s perspective will help to further illustrate this point:
I just arrived at my local pharma-cy to get a new prescription filled and to pick up a few other things. There is a line of four people at the register and another six people sitting in the waiting area. By the time I get to the counter to hand the cashier/technician my pre-scription, 5 minutes have passed. I ask how long the wait will be and I am told 30 to 40 minutes. I go about my shop-ping and return to the pharmacy 35 minutes later. Again, there are people in line at the register and it takes me another 5 minutes to find out that my prescription is not ready. Feeling weary and somewhat frustrated, I have a seat in the waiting area. As I sit there, I watch people come and go and wonder, “Wasn’t I here before that guy?” At last
my name is called! I pay the cashier and my pharmacy encounter is com-plete. However, I don’t feel good about it. Why did I have to wait so long? Did others get special priority over me? Maybe another pharmacy will service my needs better? Am I a satisfied cus-tomer?
QUEUING APPLICATIONS IN SERVICE INDUSTRIES
Queuing management has been applied very successfully in many ser-vice-oriented industries. L. L. Bean, a large telemarketer and mail-order cata-log house for high-quality sporting goods and apparel, used queuing theory to optimize staffing levels — resulting in an estimated $500,000 per year sav-ings.7 The Department of Motor
Vehi-cles in Virginia and Arizona used queu-ing technology to virtually eliminate long lines and greatly improve cus-tomer satisfaction. In addition, they were able to significantly improve employee morale and reduce operating costs.8–10
Queuing models have also been used to plan staffing levels in an outpa-tient hospital laboratory department and a centralized appointment depart-ment in Lourdes Hospital in Bingham-ton, New York. Queuing models were used to identify an optimal configura-tion of capacity and staffing levels for both departments. The lengthy delays in answering telephone calls in the cen-tralized appointments department were completely eliminated by rearranging work shifts of current employees.11,12
The Virginia Mason Medical Center in Seattle, Washington used queuing theo-ry and other classic quality manage-ment principles to drastically reduce patient waiting time for appointments (42 days to 13), emergency room triage time (45 minutes to 15), and increased staff morale.13
same time alleviating both the actual and perceived amount of time a cus-tomer spends waiting in line.14 Finally,
queuing theory has been applied to computer simulation models to help with business decisions and prob-lems.15,16
CUSTOMER SATISFACTION AND CONSUMER BEHAVIOR
In general, customer satisfaction is multifactorial and is considered a part of overall consumer behavior model. Consumer behavior evolves over time and is influenced by many factors. Sev-eral key factors that greatly influence satisfaction include consumer’s expec-tations, attitudes, and intention about the service provided.
Expectations are the consumer’s anticipated beliefs about a product or service prior to the interaction. Atti-tudes consist of the consumer’s evalua-tions, emotional feelings, and action tendencies toward a product or service that has developed over time. Intentions are the decisions the consumer makes about future actions toward the firm producing the product or service. Together, these factors influence the future behavior or the actual future action taken by the customer.
For the most part, these factors are intangible so it is the perceived mance rather than the actual perfor-mance that is more critical to customer satisfaction. The main goal of queuing management is to maximize the level of customer satisfaction with the service provided. Therefore, the primary issue in queuing management and customer satisfaction is not the actual amount of time a customer waits for service, but the customer’s perception about that wait and the associated level of satis-faction. A highly satisfied customer will be very likely to provide repeat business and spread the positive experi-ence by word of mouth (advertising), resulting in increased revenues and profitability. Conversely, a dissatisfied customer will most likely not provide
repeat business and will be more than willing to share his or her bad experi-ence with whoever will listen. This will have an obvious negative impact on profits and revenues.1–4
CUSTOMER SATISFACTION AND WAITING TIME
Customer satisfaction has been defined as the difference between the customer’s perceptions of the experi-ence and his or her expectations, which is many times based on past experience. Although it is possible to manage and decrease actual waiting time and to some extent to manage customer expectations about customer satisfac-tion, managing the customer’s percep-tion of the queuing experience can be the vital element in satisfaction with the service interaction.4 The measurement
of customer satisfaction as it relates to waiting time is highly qualitative and subjective, and the relationship is gen-erally inverse in nature (ie, in general, as waiting time decreases, satisfaction increases). This relationship was fur-ther expanded by Maister who, in 1985, postulated that satisfaction is dependent on customer perception and customer expectation.4
Numerous scientific studies, jour-nal articles, and text books have been published describing the relationship between customer satisfaction, waiting time, and consumer behavior.1–25 For
example, one study examined customer attitudes toward waiting times in the hotel and restaurant industry and found that over 70% of all respondents were clearly concerned about waiting times. In fact, those most concerned about waiting times were generally more willing to pay more to avoid waiting in line and believed that quality is worth waiting for. The results of this survey indicate that queues do affect the satis-faction level of customers and their willingness to spend. In addition, this study also suggests that there is a point where a lengthy wait begins to affect the customer’s perception of quality.17
Another study examined patient satisfaction with outpatient pharmaceu-tical services at a large university hos-pital. This study reported that of the patients who received prescriptions from university physicians and did not fill them at the university pharmacy, 21% went elsewhere to have their pre-scription filled because of the long waiting time, even though prescription prices were less expensive through the university system.18 Similarly, another
study conducted in a large Veterans Affairs hospital reported that pharmacy redesign improved patient satisfaction because of a 50% decrease in patient waiting time.6 Finally, another article
describes the relationship between waiting time and satisfaction in the con-text of social justice or injustice, as the case may be.19
QUEUING THEORY IN PHARMACY
Queuing theory and its application has gotten very little attention from pharmacy operations management; however, pharmacy practice could ben-efit by understanding and applying some of the concepts of queuing theory.
A publication, Operations Man-agement for Pharmacists, briefly dis-cusses queuing theory and customer wait-time management. The authors appropriately acknowledged that the advanced mathematical models used in queuing theory were beyond the scope of the book. Unfortunately, the only suggestion offered by the authors for managing perceived waiting time is to distract the customer by providing entertainment, refreshments, or com-fortable conditions, such as television and coffee in the waiting area.20
A literature search revealed few published articles in the area of phar-macy practice and queuing theory. Donehew and colleagues used queuing theory to address prescription queues and work measurement assessment of prescription fill times.21 Similarly,
deter-mine the impact of a computerized waiting time program on order turn-around time in a hospital pharmacy.22
Perhaps the most common and useful application of queuing theory in pharmacy operations is to reduce patient waiting time and maximize staff effectiveness. Lin and colleagues used workflow analysis and times study to identify factors leading to excessive waiting times in an ambulatory phar-macy at the University Hospital Inc. (TUH), Cincinnati, Ohio.23 In another
study, also by Lin, work measurement and computer simulation were used to assess the re-engineering of community pharmacies to facilitate patient counsel-ing.24 Although queuing theory was
never mentioned in these articles, the authors used many concepts similar to queuing theory’s and their results could be instrumental in designing queuing applications for reducing patient wait-ing time and improvwait-ing staff utilization.
In a study by Moss, queuing theo-ry was used to assess the relationships among the number of pharmacy staff members, prescription dispensing process, and outpatient waiting times. He used a mathematical queuing model to estimate the probability of waiting time exceeding a given value, when prescription arrival and service rates and number of servers are known. The study revealed that the major factors determining outpatient waiting time were the arrival pattern of prescriptions at the pharmacy, sequencing of work, and percentage of staff at work.25
Finally, Vemuri used computer simulation with a queuing model to assess patient waiting time in the outpa-tient pharmacy at the Medical College of Virginia. This study concluded that the most significant factor contributing to patient waiting times was the interac-tion between pharmacy service providers, specifically the typist and the technician.26
Many different mathematical equations can be used to describe queue
formation and behavior; however, the decision to choose one over the other is beyond the scope of this article. Although Moss25 provided the
mathe-matical formula used in his research, most queuing research applications are now completed through some form of computerization due to the complexity of the models and the accessibility of off-the-shelf software and personal computers.
WHO MIGHT BENEFIT FROM QUEUING APPLICATIONS?
It is true that many pharmacies do not experience problems with queues. However, there are many pharmacies that do experience difficulties with queue formation. For example, pharma-cies that experience high-volume pre-scription workload frequently have dif-ficulty in managing workflow and wait-ing times. This could also be true in pharmacies that offer their customers multiple points of service (ie, bank teller design). Pharmacies such as those in large managed care organizations, university health systems, and those in the VA and DoD typically fit this description.
It is safe to say that the traditional methods employed by pharmacies to distract customers (eg, comfortable waiting area, coffee, and television) would be of limited benefit in pharma-cies that fill in excess of 1,000 prescrip-tions per day and have patient waiting times that commonly exceed 1 to 2 hours.
Recently, however, automated queuing technology has been success-fully developed and applied in areas of pharmacy practice that specifically address customer waiting times. Prior to this innovation, the most advanced queuing applications to manage cus-tomer waiting times in pharmacies was a consecutive number ticketing system commonly found in barber shops and grocery stores.
QUEUING TECHNOLOGY IN PHARMACY
Automated queuing technology (AQT) is primarily utilized in the feder-al sector and includes numerous phar-macies in the DoD and the VA. Howev-er, several prominent nonfederal phar-macy organizations utilize AQT, including the University of North Car-olina, Medical College of Virginia, Jewish Hospital in Cincinnati, and Parkland Hospital in Dallas, just to name a few.27Both the DoD and the VA
operate very busy outpatient pharmacy departments, some filling in excess of 2,500 outpatient prescriptions and ser-vicing over 1,000 patients daily.
Automated queuing systems are typically PC based systems that can track a multitude of useful information that was previously very difficult to quantify for pharmacy managers. Phar-macies utilizing AQT can easily track variables such as customer arrival and departure time, patterns of arrival, pre-scription fill time, waiting time, and individual staff member productivity. In addition, AQT can track numerous points of service and different service categories (ie, certain patients may get priority service or can be used to track patient counseling) if desired.
Finally, AQT can also provide pharmacy customers with information that can directly improve their queuing experience, such as with a ticket with a unique number and the estimated wait time. This makes for a less confusing, more relaxed, and much more positive waiting environment for the patient. At the time this article was submitted for publication, only one company, the Q-Matic Corporation, that distributes automated queuing technology systems could be identified. Their website address is http://us.q-matic.com.27
CONCLUSION
of this effective management tool can yield impressive results. There are vol-umes of additional material on queuing theory and in fact this paper has only touched the surface. The goal of this paper was to give the reader a general understanding of concepts, current technology, and applications of queuing theory as it relates to customer satisfac-tion and waiting time.
Undoubtedly, there are numerous factors—physical, psychological, and emotional, to name a few—that affect a customer’s perception of the waiting experience. By better understanding queuing theory and the various mea-sures associated with customer waiting time, service managers can make deci-sions that have a beneficial impact on the satisfaction of all relevant partici-pants: customers, employees and man-agement. There are several tools such as computer simulation, modeling , and automated queuing technology that can assist in this process improvement endeavor.
Waiting in line will always be prevalent in our society and in our phar-macies. As the health care industry con-tinues to evolve, pharmacists are under continued and growing pressure to do more and more. Wouldn’t it be nice to practice pharmacy in a setting where the worry and burden of wait time man-agement was eased, even eliminated — keeping customers happy and decreas-ing the anxiety of those behind the counter trying to provide the best phar-macy service?
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