4. WHERE THE TIME GOES
In a life time, the average
person will spend:
SIX MONTHS Waiting at stoplights
EIGHT MONTHS Opening junk mail
ONE YEAR Looking for misplaced 0bjects
TWO YEARS Reading E-mail
FOUR YEARS Doing housework
FIVE YEARS Waiting in line
SIX YEARS Eating
12-4
5. TEN PROPOSITIONS ON THE
PSYCHOLOGY OF WAITING LINES
1. Unoccupied time feels longer
2. Preprocess/post-process waiting feels longer than in-process
3. Anxiety makes waiting seem longer
4. Uncertain waiting is longer than known, finite waiting
5. Unexplained waiting seems longer
6. Unfair waiting is longer than equitable waiting
7. People will wait longer for more valuable services
8. Waiting alone feels longer than in groups
9. Physically uncomfortable waiting feels longer
10. Waiting seems longer to new or occasional users
Sources: Maister; Davis & Heineke; Jones & Peppiatt
6. COMPONENTS OF THE QUEUING SYSTEM
Servicing System
Servers
Queue or
Customer Waiting Line
Arrivals Exit
7. LAWS OF SERVICE
Maister’s First Law:
Customers compare expectations with
perceptions.
Maister’s Second Law:
Is hard to play catch-up ball.
Skinner’s Law:
The other line always moves faster.
Jenkin’s Corollary:
However, when you switch to another other
line, the line you left moves faster.
12-7
8. CUSTOMER SERVICE POPULATION SOURCES
Population Source
Finite Infinite
Example: Number of Example: The
machines needing number of people
repair when a who could wait in
company only has
three machines.
a line for gasoline.
9. SERVICE PATTERN
Service
Pattern
Constant Variable
Example: Items Example: People
coming down an spending time
automated assembly shopping.
line.
10. THE QUEUING SYSTEM
Length
Queue Discipline Queuing Number of Lines &
Line Structures
System
Service Time
Distribution
11. EXAMPLES OF LINE STRUCTURES
Single
Multiphase
Phase
One-person
Single Channel Car wash
barber shop
Bank tellers’ Hospital
Multichannel
windows admissions
12. ESSENTIAL FEATURES OF QUEUING
SYSTEMS
Renege
Arrival Queue
process Departure
Calling Queue discipline Service
population configuration process
Balk No future
need for
service
12-12
13. ARRIVAL PROCESS
Arrival
process
Static Dynamic
Random Random arrival Customer-
Facility- exercised
arrivals with rate varying
controlled control
constant rate with time
Accept/Reject Price Appointments Reneging Balking
12-13
14. QUEUE DISCIPLINE
Queue
discipline
Static
Dynamic
(FCFS rule)
selection Selection based
based on status on individual
of queue customer
attributes
Number of Processing time
customers Round robin Priority Preemptive of customers
waiting (SPT or cµ rule)
12-14
15. WAITING LINE SYSTEM
Includes the customer population source as well
as the process or service system.
QUEUING SYSTEM
Another name to define a waiting line.
FINITE CUSTOMER POPULATION
The number of potential new customers is
affected by the number of customers already
in the system.
17. INFINITE CUSTOMER POPULATION
The number of potential new customers is not
affected by the number of customers already in
the system.
BALKING
The customer decides not to enter the waiting
line.
RENEGING
The customer enters the line but decides to
exit before being served.
18. JOCKEYING
The customer enters one line and then switches
to a different line in an effort to reduce the
waiting time.
THE NUMBER OF WAITING LINES
THE NUMBER OF SERVERS
THE ARRANGEMENT OF THE SERVERS
19.
20. ARRIVAL AND SERVICE PATTERNS
Arrival rate
The average number of customers arriving per
time period.
Service rate
The average number of customers that can be
served per time period.
Waiting Line Priority Rules Generally customers consider
first-come, first-served to be the fairest method for determining
priority. Other rules include best Customers first, highest profit
customer first, quickest service requirement first, largest service
requirement first, emergencies first...
21. CRITERIA FOR SEGMENTATION AND
ALLOCATION OF QUEUING POPULATION
Urgency of job
emergencies vs. non-emergencies
Duration of service transaction
number of items to transact
complexity of task
Payment of premium price
First class vs. economy
Importance of customer
frequent users/loyal customers vs. others
22.
23. WAITING LINE PERFORMANCE MEASURES
1.The average number of customers waiting
in line and in the system.
2. The average time customers spend
waiting, and the average time a customer
spends in the system.
3. The system utilization rate.
24. BENEFITS OF A RESERVATIONS SYSTEM
Controls and smoothes demand
Pre-sells service
Informs and educates customers in
advance of arrival
Customers avoid waiting in line for service
(if service times are honored)
Data capture helps organizations prepare
financial projections
25. CHARACTERISTICS OF WELL-
DESIGNED RESERVATIONS SYSTEMS
Fast and easy for customers and staff
Can answer customers’ questions
Offers options for self service (e.g. Web)
Accommodates preferences (e.g., room with view)
Deflects demand from unavailable first choices to
alternative times and locations
Includes strategies for no-shows and overbooking
required deposits discourage no-shows
unpaid bookings canceled after designated time
compensation for victims of over-booking
26. CHANGING OPERATIONAL CHARACTERISTICS
Customer arrival rates.
Number and type of service facilities.
Changing the number of phases.
Server efficiency.
Changing the priority rule.
Changing the number of lines.
