טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentChocron Elisheva
SubjectPredicting Waiting Time in Queueing Systems: Comparison of
Queueing Theory and Machine Learning Models
DepartmentDepartment of Industrial Engineering and Management
Supervisors DR. Izack Cohen
PROFESSOR EMERITUS Paul Feigin
Full Thesis textFull thesis text - English Version


Abstract

We research approaches for predicting waiting times of customers within service systems. Our focus is on call centers in which accurate waiting time predictions may enable improved work-force management and lead to increased customer satisfaction.

Standard approaches for design and management of service systems that include customers, servers and queues rely on Queueing Theory (QT).

QT is often criticized since its formulas are based on fundamental assumptions regarding the model describing a given system ? assumptions which are usually violated.

To overcome this issue, we hypothesize that additional external characteristics (“features”) may be required in order to provide an accurate prediction of the waiting time for many real-life systems. We further hypothesize that a Machine Learning (ML) model incorporating those characteristics will improve the performance of waiting time predictions. Consequently, in this research we explore the use of ML-based algorithms for waiting time prediction and investigate to what extent they overcome the limits of QT methods which are typically based on “simple model” assumptions. In a series of experiments, we use multiple ML- and QT-based models to predict the waiting times of customers with simple (“synthetic”) and real-life call centers.

We analyze the performance of the different models, in order to determine for which methods and under what conditions ML performance compares favorably with QT performance.

One conclusion is the apparent robustness of QT-based predictions when restrictions such as First-Come-First-Serve (FCFS) priority rule, single station and a single queue are assumed. Under these assumptions, even when the simulated system deviates markedly from the simple model, the QT prediction remains the most robust. Nonetheless, learning algorithms such as Artificial Neural Network (ANN) and Gradient Boosting Regression (GBR) outperform the QT predictions when the FCFS priority does not hold.