OR 542

Operations Research: Stochastic Models

Spring 2025

Stochastic Operations Research (OR) is concerned with complex systems that operate under randomness and uncertainty, and aims to develop mathematical models and techniques for the analysis and optimization of such systems. In data analytics, stochastic OR is an important foundation for Prescriptive Analytics, which is a process that analyzes data and provides instant recommendations on how to optimize business practices to suit multiple predicted outcomes with consideration of system randomness and future uncertainty.

Companies in many industries can employ stochastic OR to improve their business practices and increase profitability. For example, in the financial services sector, planners, analysts, and portfolio managers use stochastic modeling to manage their assets and liabilities and optimize their portfolios. When choosing investment vehicles, it is critical to be able to view a variety of outcomes under multiple factors and conditions, some of which are stochastic. Another example is that the insurance industry relies heavily on stochastic modeling to predict how company balance sheets will look at a given point in the future.

Imagine that you are a store manager. How do you manage your inventory level? High inventory implies higher costs. On the other hand, low inventory usually leads to out of stocks. What is your optimal inventory decision while considering the uncertainty of future demand?

Another example we will explore in the class: imagine that you are the manager of an airline call center. If you expect the number of calls will increase by 20~50% since a holiday is coming, how many additional agents should you add to handle the higher demand? More agents implies higher costs, while less agents may increase customer waits. We will model the call center as a queueing system and apply queueing theory to find a good decision.

In this class, we will cover several important stochastic models in Operations Research:

In the term project, students will develop Monte Carlo simulation (using basic Excel) to analyze how various investment portfolios may perform based on the probability distributions of individual stock returns and determine good decisions.


Instructor: Professor Chun-Hung Chen
Email: cchen9@gmu.edu
Office: Engineering Building, Room 2213
Phone: 703-993-3572
Fax: 703-993-1521
Office Hours: Wednesday 3:30 - 4:30PM; Friday 9:30-10:30AM

Teaching Assistant: Mr. Bahador Dodge
Email: bdodge @gmu.edu
Office: Engineering Building, Room 2216
Zoom link: provided in the BB
Office Hours: Wednesdays 6:00-7:00pm and Thursdays 3:00-4:00pm (The TA is assisting multiple classes with many students. To minimize your waiting time, you are advised to send an email to TA in advance. Thus he can give you a suggested best time to arrive.)

Required Text: W. L. Winston, "Operations Research: Applications and Algorithms" 4rd edition, 2004. Two copies of the text books have been placed on reserve at the Johnson Center Library. It may be borrowed for 2 hours at a time. To borrow the book, you will need the call number: T57.6.W645 2004.

Library Resource Assistant: Theresa Calcagno; tcalcagn@gmu.edu; 703-993-3712

Prerequisites: STAT 344, or MATH 351, or equivalent.

Grading: Homework 5%; Term Project 15%, Two exams 80% (higher one 45%, lower one 35%). A typical scale will be applied to determine the final letter grade, i.e., B- for >80; B for >83; B+ for >87; A- for >90; A for >93; etc.

Examinations: There will be two take-home exams. The exam runs from 4:30pm of the day to 11:00pm of the next day. Make up exam questions will be MUCH HARDER than regular exam questions.

There is no final exam. We will do a term project near the end of the semester.

Term Project is about the use of Monte Carlo simulation. Students will develop simulation (using basic Excel) to analyze how various investment portfolios may perform and determine good decisions. Details will be given during the semester. The goal is to learn how a stochastic modeling tool can be easily applied to real-life problems, and to appreciate the power of simulation.

Recordings of New Lectures:
All of our new lectures will be recorded. If you miss a class, you should go to watch those recordings to catch up with the teaching materials and the announcements made in classes.

To access the new recordings, after you log onto your blackboard and get into our class, please choose "tool" and click "Class Collaborate Ultra". After you enter Collaborate, click the menu on the upper left corner of the Collaborate window and then choose "Recordings".

Blackboard (to log in Bb, please click here):

Homework assignments, solutions, ppt files of lectures, lecture recording, and sample exam questions can be downloaded at Blackboard. Specifically,

1.     You can download the ppt files of lectures at "Course Content" section.

2.     Lecture recordings of from previous years are available at "Course Content" section.

3.     Homework assignments and term project are available at "Assignment" section.

4.     Solutions to homework will be posted at "Assignment" section after submission deadline.

5.     Sample exam questions and their solutions can be downloaded at "Assignment" section.

Class Format:

1.     This is a hybrid class, including in-person meetings at classroom (Enterprise Hall 277) and online teaching via Blackboard.

2.     No matter which section you enroll, you are welcome to attend the classroom section (Enterprise Hall 277) and meet with the instructor face-to-face.

3.     No matter which section you enroll, to save your transportation time, you are welcome to attend the online section through Blackboard. After you log into your blackboard and get into our class, please choose "tool" and click "Class Collaborate Ultra". Then you will see the link to join the class.

General Rules:

1.     Homework must be submitted as a single pdf file through Blackboard.

2.     Late homework is always allowed. No need to get advanced permission. However, the penalty for late homework is 25% for the first day and then 5% per day. No exemption.

3.     No collaborations are allowed for homework, although discussions are encouraged.

4.     Comments are strongly encouraged.

5.     No cheating.


Course Outline & Reading Assignment:

 

Topics

Time (week)

Reading Assignment

A

Introduction & Probability review

2

Chapter 12

B

Decision making under uncertainty

1.5

Chapter 13

C

Inventory Models

3

Chapters 15 & 16

D

Markov chains

2

Chapter 17

E

Queueing theory

2

Chapter 20

F

Simulation (using basic Excel)

1.5

Chapters 21, 22, & 23

 


Go to Professor Chun-Hung Chen's Page

 

 

 

 


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To interrogate histories of white supremacy and white-dominant culture, and to examine the ways in which these histories have impacted our individual beliefs, our interpersonal relationships, our institutional and structural policies and processes, and our entire society;

To make a commitment to being responsible for our own relationships to, and actions within, systems of white supremacy; and

To cultivate a practice of self-awareness and self-reflection that allows us to critically evaluate our own role in upholding white supremacy and identify the ways we can interrupt cycles of racism at the individual, interpersonal, institutional, and structural levels.

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For more information on how to continuously cultivate the practice of anti-racism, see this guide from the National Museum of African American History and Culture on how to be anti-racist:

https://nmaahc.si.edu/learn/talking-about-race/topics/being-antiracist