ISYE 6644 - M1 (Modules 1 - 5.L9
Question and answers rated A+ 2026
Steps in a Simulation Study - correct answer ✔The iterative process involved in carrying out a
simulation, including problem formulation, objectives and planning, model building, data collection,
coding, verification, model validation, experimental design, running experiments, output analysis, and
reporting/implementation.
Problem Formulation - correct answer ✔The initial statement of the problem, such as "Profits are too
low" or "Customers are complaining about the long lines".
Objectives and Planning - correct answer ✔Identifying specific questions to answer, such as "How many
workers to hire?" or "How much buffer space to insert in the assembly line?".
Model Building - correct answer ✔The process of creating an abstract representation of the system,
involving both art and science, potentially using mathematical models like M/M/k queuing or physics
equations.
Data Collection - correct answer ✔Determining the types and amount of data needed, considering
continuous or discrete data, what to collect, and budget considerations.
Coding - correct answer ✔Deciding on a simulation language or modeling paradigm (like Event-
Scheduling or Process-Interaction) and writing the simulation program.
Verification - correct answer ✔Checking if the code is correct and free of obvious programming errors.
If not, returning to the coding step. This is a programming issue.
Validation - correct answer ✔Checking if the model accurately represents the real system, often using
statistical techniques. If the model is not valid, returning to model building and data collection.
,Experimental Design - correct answer ✔Determining the experiments to run efficiently to answer the
study's questions, considering statistical requirements and time/budget constraints.
Run Experiments - correct answer ✔Executing the simulation program for production runs, which can
be substantial and require significant time.
Output Analysis - correct answer ✔Performing statistical analysis on the results of the experiments to
estimate relevant measures of performance and calculate confidence intervals. This is often an iterative
process with experimental design and production runs, and typically requires more runs.
Make Reports, Implement, and Make Management Happy - correct answer ✔The final steps of
documenting the results, putting the findings into practice if possible, and ensuring the outcome
satisfies stakeholders.
System - correct answer ✔A collection of entities that interact together to accomplish a goal.
Model - correct answer ✔An abstract representation of a system, usually containing mathematical or
logical relationships describing the system in terms of states, entities, sets, events, etc..
System state - correct answer ✔A set of variables that contains enough information to describe the
system at any point in time, acting as a "snapshot". For example, in a single-server queue, this could be
the number of people in the queue at time t, and whether the server is busy or idle at time t.
Entities - correct answer ✔Things in the system that interact, such as people (e.g., customers) or
machines. They can be permanent (like a machine) or temporary (like customers).
Attributes - correct answer ✔Properties or characteristics of entities, such as the priority of a customer
or the average speed of a server.
, List (or queue) - correct answer ✔An ordered list of associated entities, such as a line of people waiting
for service.
Event - correct answer ✔A point in time at which the system state changes, and which generally can't
be predicted with certainty beforehand. Examples include an arrival event, a departure event, or a
machine breakdown event. Loosely, it can also refer to "what" happens. In discrete-event simulation,
the clock moves from event to event.
Activity - correct answer ✔A duration of time of specified length, also known as an unconditional wait.
Examples include exponential customer interarrival times or constant service times, which are explicitly
generated and thus "specified".
Unconditional wait - correct answer ✔Another term for an activity, representing a duration of time of
specified length.
Conditional wait - correct answer ✔A duration of time of unspecified length, such as a customer
waiting time, which is not directly known but is reverse-engineered from arrival and service times.
Time-Advance Mechanisms - correct answer ✔The methods for moving the simulation clock forward.
The two main ways are Fixed-Increment Time Advance and Next-Event Time Advance.
Next-Event Time Advance - correct answer ✔Initializing the clock at 0, determining all known future
event times and placing them in an ordered list (the future events list aka FEL), and then advancing the
clock to the time of the most imminent event. At each event, the system state and the FEL are updated.
This is the basis of discrete-event simulation.
Future events list (FEL) - correct answer ✔An ordered list containing the times of all known future
events. The clock advances to the most imminent event on this list, and the list is updated (by inserting,
deleting, or moving events) as events occur. Efficient list processing, such as linked lists, is needed for
the FEL. Commercial simulation packages typically handle the FEL logic automatically, making it
transparent to the user.
Question and answers rated A+ 2026
Steps in a Simulation Study - correct answer ✔The iterative process involved in carrying out a
simulation, including problem formulation, objectives and planning, model building, data collection,
coding, verification, model validation, experimental design, running experiments, output analysis, and
reporting/implementation.
Problem Formulation - correct answer ✔The initial statement of the problem, such as "Profits are too
low" or "Customers are complaining about the long lines".
Objectives and Planning - correct answer ✔Identifying specific questions to answer, such as "How many
workers to hire?" or "How much buffer space to insert in the assembly line?".
Model Building - correct answer ✔The process of creating an abstract representation of the system,
involving both art and science, potentially using mathematical models like M/M/k queuing or physics
equations.
Data Collection - correct answer ✔Determining the types and amount of data needed, considering
continuous or discrete data, what to collect, and budget considerations.
Coding - correct answer ✔Deciding on a simulation language or modeling paradigm (like Event-
Scheduling or Process-Interaction) and writing the simulation program.
Verification - correct answer ✔Checking if the code is correct and free of obvious programming errors.
If not, returning to the coding step. This is a programming issue.
Validation - correct answer ✔Checking if the model accurately represents the real system, often using
statistical techniques. If the model is not valid, returning to model building and data collection.
,Experimental Design - correct answer ✔Determining the experiments to run efficiently to answer the
study's questions, considering statistical requirements and time/budget constraints.
Run Experiments - correct answer ✔Executing the simulation program for production runs, which can
be substantial and require significant time.
Output Analysis - correct answer ✔Performing statistical analysis on the results of the experiments to
estimate relevant measures of performance and calculate confidence intervals. This is often an iterative
process with experimental design and production runs, and typically requires more runs.
Make Reports, Implement, and Make Management Happy - correct answer ✔The final steps of
documenting the results, putting the findings into practice if possible, and ensuring the outcome
satisfies stakeholders.
System - correct answer ✔A collection of entities that interact together to accomplish a goal.
Model - correct answer ✔An abstract representation of a system, usually containing mathematical or
logical relationships describing the system in terms of states, entities, sets, events, etc..
System state - correct answer ✔A set of variables that contains enough information to describe the
system at any point in time, acting as a "snapshot". For example, in a single-server queue, this could be
the number of people in the queue at time t, and whether the server is busy or idle at time t.
Entities - correct answer ✔Things in the system that interact, such as people (e.g., customers) or
machines. They can be permanent (like a machine) or temporary (like customers).
Attributes - correct answer ✔Properties or characteristics of entities, such as the priority of a customer
or the average speed of a server.
, List (or queue) - correct answer ✔An ordered list of associated entities, such as a line of people waiting
for service.
Event - correct answer ✔A point in time at which the system state changes, and which generally can't
be predicted with certainty beforehand. Examples include an arrival event, a departure event, or a
machine breakdown event. Loosely, it can also refer to "what" happens. In discrete-event simulation,
the clock moves from event to event.
Activity - correct answer ✔A duration of time of specified length, also known as an unconditional wait.
Examples include exponential customer interarrival times or constant service times, which are explicitly
generated and thus "specified".
Unconditional wait - correct answer ✔Another term for an activity, representing a duration of time of
specified length.
Conditional wait - correct answer ✔A duration of time of unspecified length, such as a customer
waiting time, which is not directly known but is reverse-engineered from arrival and service times.
Time-Advance Mechanisms - correct answer ✔The methods for moving the simulation clock forward.
The two main ways are Fixed-Increment Time Advance and Next-Event Time Advance.
Next-Event Time Advance - correct answer ✔Initializing the clock at 0, determining all known future
event times and placing them in an ordered list (the future events list aka FEL), and then advancing the
clock to the time of the most imminent event. At each event, the system state and the FEL are updated.
This is the basis of discrete-event simulation.
Future events list (FEL) - correct answer ✔An ordered list containing the times of all known future
events. The clock advances to the most imminent event on this list, and the list is updated (by inserting,
deleting, or moving events) as events occur. Efficient list processing, such as linked lists, is needed for
the FEL. Commercial simulation packages typically handle the FEL logic automatically, making it
transparent to the user.
