OM Test 3 Flashcards
Which of the following statements about scheduling are correct?
Scheduling is constrained by prior decisions such as capacity & aggregate planning.
Scheduling decisions are the final step in the transformation process.
Scheduling in high-volume systems is known by what term?
Flow Shop Scheduling
Compared to a job shop, the batch sizes in intermediate-volume systems are ___________.
Larger
The two basic issues for schedulers in low-volume systems are what?
Distribution among work centers and sequencing
In assigning jobs to work centers in a low-volume system what three aspects are minimized?
Processing costs, idle time, job completion time
What is the best definition of scheduling from among the options given?
Establishing the timing of the use of equipment, facilities, and human activities in an organization.
What is the goal of a high-volume system?
High utilization of labor and equipment
The purpose of Gantt charts is to organize and visually display the actual or intended use of resources in a ______.
Time Framework
Which word below most accurately describes the processing involved in intermediate-volume systems.
intermittent
Scheduling in low-volume systems is known by what term?
Job-shop scheduling
The assignment of jobs to processing centers in low-volume systems is know by what term?
Loading
Which chart is used as a visual aid for both loading and scheduling in low-volume systems?
Gantt chart
_______ loading projects the actual job starting and finishing times at each work center by taking into account the capacities of the work center and the processing time of the jobs.
Finite
True or false: Without input/output control, capacity may exceed demand, causing an overload at a work center.
False
Which of the following is the best definition of a workstation in the context of job loading and scheduling at a work center.
An area where one or a few workers and/or machines perform similar work
Which type of loading can lead to overloads in some time periods and underloads in others?
Infinite Loading
What is the best definition of a priority rule?
Simple heuristics used to select the order in which jobs will be processed.
What is the term used for managing work flow and queues at work centers?
Input/output (I/O) control
Determining the order in which jobs at and within a work center will be processed is known as what?
Sequencing
Which priority rule is used most often for service systems in which customers are directly involved?
FCFS
Which priority rule calculates a ratio of time remaining until due date over processing time remaining for each job to determine sequencing?
CR
What does priority rule acronym FCFS stand for?
First Come, First Serve
Which of the following statements are correct about Johnson’s rule?
Johnson’s rule minimizes total idle time for both machines or work centers.
The job with the shortest time for Machine 1 is the first in the sequence.
True or false: Johnson’s rule can be used when setup times at a workstation are sequence dependent.
False
What priority rule can result in lower in-process inventories?
SPT
Under which priority rule are long jobs most likely to wait for processing?
SPT
The sequencing technique which minimizes the total time for a group of jobs to be processed on two machines or workcenters is called what?
Jhonson’s Rule
elect all of the reasons why scheduling can be difficult for operations managers.
Variability in setup times and processing times
Interruptions in the work flow (machine break downs, quality issues, etc.)
Select all the actions that managers can take to minimize scheduling difficulties.
Set realistic due dates whenever possible.
Focus on process bottlenecks and schedule around it if unable to eliminate it.
What technique is used when setup times at a workstation are sequence dependent?
Determine the total time of each job sequence permutation considering the setup time and choose the best (lowest) time.
Scheduling techniques assume a process can be modeled, but in reality, there can be ______ in setup times and processing times.
Variability
The theory of constraints focuses on what mainly?
The Bottleneck Operation
Which of the following will minimize scheduling difficulties?
Split large jobs into smaller batches
How do operations managers in the service sector mitigate the random variability in customer requests for service?
Use appointment and reservation systems
What is the primary purpose of appointment systems in scheduling services?
To minimize customer waiting time
What does “drum-buffer-rope” mean in the theory of constraints.
A scheduling practice to keep inventory ahead of the bottleneck to minimize idle time at the constraint
Select all the actions that managers can take to minimize scheduling difficulties.
Focus on process bottlenecks and schedule around it if unable to eliminate it.
Set realistic due dates whenever possible.
What is the primary purpose of reservation systems in scheduling services?
To estimate customer demand and provide a better service experience
Customers who make advance reservations are typically ____________ while walk-ins are typically ____________.
price-sensitive/price-insensitive
What two difficulties arise in scheduling services that do not occur in manufacturing?
Inability to store services and random customer requests for service
Select all of the constraints on workforce scheduling flexibility.
Legal issues
Behavioral issues
Technical issues
Union rules
When appointment systems are used, what circumstances lead to problems in scheduling services?
When customers arrive late
When customers do not show up
Which of the following is required for cyclical scheduling?
Workers must have a standard schedule
Select all of the industries which use reservation systems to manage demand and capacity.
Car rental agencies
Restaurants
Hotels and resorts
The more resources to be scheduled in conjunction to perform a service, the ___________ the complexity and the ____________ likely that an optimum schedule can be achieved.
greater/less
The application of pricing strategies to allocate capacity among various categories of demand is known by what term?
Yield Managment
True or false: If done well, scheduling can be a competitive advantage and a source of customer satisfaction and cost savings for an organization.
True
To improve customer satisfaction at busy service times, capacity can be adjusted by what activity?
Cross-training workers to assist on bottleneck operations
Which of the following is an example of cyclical scheduling?
Assigning a worker at a restaurant the same days off each week
Which of the following is an example of scheduling multiple resources to perform a service.
Coordinating crew, aircraft, gate, baggage handling equipment for an airline flight
What does time-based scheduling depend on?
Good Scheduling
A mathematical approach to the analysis of waiting lines is called what?
Queuing theory
True or False?
Waiting lines will occur even though a system is basically underloaded.
True
What are some negative customer-side implications of waiting lines?
Customers may leave the line, potentially resulting in loss of goodwill.
Customer dissatisfaction may occur from waiting too long.
What is included in customer waiting costs?
Salaries paid to employees who are waiting
Cost of space provided for waiting lines
Loss of business due to customers refusing to wait
What are the four main characteristics of waiting lines which determine the queuing model?
Order of service
Number of channels
Arrival/service patterns
Population source
Which of the following statements about queuing theory are correct?
A.K. Erlang developed queuing theory while working on automatic dialing equipment.
Queuing theory is directly applicable to many service operations.
Why would there be waiting in an underloaded system?
Customers arrive randomly.
Services cannot be stored.
In what ways do waiting lines cost businesses?
Disruption to operations can occur if lines are too long.
Business must provide adequate space for customers to wait.
What is the goal of waiting line management?
To minimize total costs of providing capacity and customer waiting costs.
The queuing model that is chosen is based upon what?
Characteristics of the capacity and demand
What is the main difference between a finite and an infinite source population in queuing theory?
Finite is a relatively small group potentially needing service, while infinite source greatly exceeds the number of servers.
The capacity of a service system in queuing theory is a function of what?
The number of servers and the capacity of each server
What does a Poisson distribution of arrivals mean in practical terms?
Usually there are only a few or no customers in line.
The potential source of customers who enter waiting lines for service is referred to as what?
Calling Population
If service time is exponential, then the service rate is what?
Poisson
The models covered in this textbook assume customers are what?
Patient
What is a channel in queuing theory?
A synonym for “server”
What does a negative exponential distribution of service time mean in practical terms?
Most of the time service does not take very long
What is meant by the term queue discipline?
The rule-based order in which customers are processed in the system
Under what conditions are waiting lines most likely to occur?
When arrivals are bunched together
When service times are particularly lengthy
jockeying
Switching lines, especially if another becomes shorter
reneging
After waiting awhile, deciding to leave the queue and exit
balking
Never getting in line and exiting the system, due to line length
The five measures used to evaluate queuing systems relate to ______.
potential customer dissatisfaction and costs
Most queuing models assume which queue discipline?
First come First Served
True or false: A service operation manager will typically want to achieve 100% system utilization.
False
What is the theoretical distribution which describes the service time in queuing theory?
Negative Exponential
System utilization is a measure of how ____________ servers are.
Busy
What is the theoretical distribution which describes the arrival or service rate?
Poisson distribution
When first-come, first-served is not used, how is the next customer selected for processing?
Customer with highest cost
There are four infinite-source queuing models covered in this chapter. What assumptions do they all have in common?
System is operating under steady-state conditions.
Arrival rates can be described by a Poisson distribution.
What is the formula for the average number of customers being serviced?
r = λ/μ
According to Little’s Law, for a stable system, identify the correct equation to determine the average time customers are waiting in the system.
Ls = λWs
What are the assumptions for using the single server, exponential service time queuing model?
Service time can be modeled by negative exponential distribution
Queue discipline is first come, first served
Rates are Poisson distributed
What is the formula for system utilization?
ρ = λ/(Μμ)
What is the formula for the average number in line in a single-server, model?
Lq = λ2/μ(μ−λ)
Using Little’s Law, the average time customers are waiting in line is ______.
Wq = Lq/λ
For the single server, exponential service time queuing model, what statement is correct about length of queue?
There is no limit on length of queue.
Which of the following statements is true about the multiple server queuing model?
All servers work at the same average rate
What are the benefits of a system with a constant service time?
It cuts the average number of customers waiting in line in half.
According to Little’s law, for a stable system, the average number of customers in line or in the system is equal to the average customer arrival rate multiplied by the average time in line or in the system. What are the implications for the analysis of waiting lines?
The relationships are independent of any probability distribution
It requires no assumption regarding the order in which they are served
It requires no assumptions about which customers arrive or are serviced
From the queuing cost analysis graph, as servers are added beyond the optimal number, what happens to total cost?
It Increases
Why would a service operations manager need to calculate maximum line length for his or her system?
To know how much space to provide for waiting lines
What are the assumptions of the infinite-source multiple server queuing model?
Customers form a single waiting line.
A Poisson arrival rate and exponential service time is used.
Servers all work at the same average rate.
Which of the following is an example of a multiple-priority service system?
A hospital emergency room where waiting is based upon patient condition severity
For cost analysis in queueing, the goal is to minimize what two costs?
customer waiting and capacity
Theoretically, in an infinite-source queuing model how long is the maximum line length with 100% probability?
Infinitely Long
Which of the following is an example of “demand shift” as a way to reduce customer waiting times and temporary system overloads.
A restaurant offers an “early bird special” to encourage patrons to arrive earlier than normal
In queuing theory, when “first-come, first-served” is not an appropriate queue discipline, what is the other option?
Multiple-priority model
What is the major difference between finite and infinite source models in queuing theory?
In finite model the arrival rate decreases as the line length increases.
Why would a service operations manager need to calculate maximum line length for his or her system?
To know how much space to provide for waiting lines
Studies have shown a remarkable difference between actual waiting time and _________________ waiting time.
Perceived
What are the assumptions of the infinite-source multiple server queuing model?
Servers all work at the same average rate.
A Poisson arrival rate and exponential service time is used.
Customers form a single waiting line.
What are some of the ways service managers may be able to reduce waiting times through constraint management?
Shift demand off peak hours via customer incentives
Eliminate a bottleneck through process improvement methods
Use temporary workers during peak demand times
f a service manager cannot shift demand to spread out customer arrivals, then he or she should focus on processing speed or standardization to increase the __________ ___________.
Service Rate
Which of the following approaches do managers use to handle customer-perceived waiting time?
Use distractions like video screens or have customer fill out forms.
Inform customers of estimated waiting times (restaurants, phone centers, etc.) to reduce anxiety.
What impact will increasing the standardization have on the service time?
Reduce variability
