Chapter 13
Aggregate Planning
Operations Management - 5th Edition
Roberta Russell & Bernard W. Taylor, III
Copyright 2006 John Wiley & Sons, Inc.
Beni Asllani
University of Tennessee at Chattanooga
Lecture Outline



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Aggregate Planning Process
Strategies for Adjusting Capacity
Strategies for Managing Demand
Quantitative Techniques for Aggregate
Production Planning
 Hierarchical Nature of Planning
 Aggregate Planning for Services
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Aggregate Planning
 Determine the resource capacity needed to
meet demand over an intermediate time
horizon


Aggregate refers to product lines or families
Aggregate planning matches supply and demand
 Objectives


Establish a company wide game plan for allocating
resources
Develop an economic strategy for meeting
demand
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Aggregate Planning Process
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Meeting Demand Strategies
 Adjusting capacity


Resources necessary to meet demand
are acquired and maintained over the
time horizon of the plan
Minor variations in demand are handled
with overtime or under-time
 Managing demand

Proactive demand management
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Strategies for Adjusting Capacity
 Level production
 Overtime and under-time
Producing at a constant rate
 Increasing or decreasing
and using inventory to
working hours
absorb fluctuations in
 Subcontracting
demand
 Let outside companies
 Chase demand
complete the work
 Hiring and firing workers to
 Part-time workers
match demand
 Hiring part time workers to
 Peak demand
complete the work
 Maintaining resources for
 Backordering
high-demand levels
 Providing the service or
product at a later time period

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Level Production
Demand
Units
Production
Time
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Chase Demand
Demand
Units
Production
Time
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Strategies for Managing Demand
 Shifting demand into
other time periods



Incentives
Sales promotions
Advertising campaigns
 Offering products or
services with countercyclical demand patterns
 Partnering with suppliers
to reduce information
distortion along the
supply chain
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Quantitative Techniques For APP





Pure Strategies
Mixed Strategies
Linear Programming
Transportation Method
Other Quantitative
Techniques
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Pure Strategies
Example:
QUARTER
Spring
Summer
Fall
Winter
SALES FORECAST (LB)
80,000
50,000
120,000
150,000
Hiring cost = $100 per worker
Firing cost = $500 per worker
Regular production cost per pound = $2.00
Inventory carrying cost = $0.50 pound per quarter
Production per employee = 1,000 pounds per quarter
Beginning work force = 100 workers
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Level Production Strategy
Level production
(50,000 + 120,000 + 150,000 + 80,000)
= 100,000 pounds
4
QUARTER
Spring
Summer
Fall
Winter
SALES
FORECAST
80,000
50,000
120,000
150,000
PRODUCTION
PLAN
INVENTORY
100,000
100,000
100,000
100,000
400,000
Cost of Level Production Strategy
(400,000 X $2.00) + (140,00 X $.50) = $870,000
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20,000
70,000
50,000
0
140,000
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Chase Demand Strategy
QUARTER
SALES PRODUCTION
FORECAST
PLAN
Spring
Summer
Fall
Winter
80,000
50,000
120,000
150,000
80,000
50,000
120,000
150,000
WORKERS
NEEDED
80
50
120
150
WORKERS WORKERS
HIRED
FIRED
0
0
70
30
20
30
0
0
100
50
Cost of Chase Demand Strategy
(400,000 X $2.00) + (100 x $100) + (50 x $500) = $835,000
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Mixed Strategy
 Combination of Level Production and
Chase Demand strategies
 Examples of management policies


no more than x% of the workforce can be
laid off in one quarter
inventory levels cannot exceed x dollars
 Many industries may simply shut down
manufacturing during the low demand
season and schedule employee
vacations during that time
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General Linear Programming (LP)
Model
 LP gives an optimal solution, but demand
and costs must be linear
 Let





Wt = workforce size for period t
Pt =units produced in period t
It =units in inventory at the end of period t
Ft =number of workers fired for period t
Ht = number of workers hired for period t
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LP MODEL
Minimize Z = $100 (H1 + H2 + H3 + H4)
+ $500 (F1 + F2 + F3 + F4)
+ $0.50 (I1 + I2 + I3 + I4)
Subject to
Demand
constraints
Production
constraints
Work force
constraints
P1 - I1
I1 + P2 - I2
I2 + P3 - I3
I3 + P4 - I4
1000 W1
1000 W2
1000 W3
1000 W4
100 + H1 - F1
W1 + H2 - F2
W2 + H3 - F3
W3 + H4 - F4
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= 80,000
= 50,000
= 120,000
= 150,000
= P1
= P2
= P3
= P4
= W1
= W2
= W3
= W4
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
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Transportation Method
QUARTER
EXPECTED
DEMAND
REGULAR
CAPACITY
OVERTIME
CAPACITY
SUBCONTRACT
CAPACITY
1
2
3
4
900
1500
1600
3000
1000
1200
1300
1300
100
150
200
200
500
500
500
500
Regular production cost per unit
Overtime production cost per unit
Subcontracting cost per unit
Inventory holding cost per unit per period
Beginning inventory
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$20
$25
$28
$3
300 units
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Transportation Tableau
PERIOD OF USE
PERIOD OF PRODUCTION
1
Beginning
1
2
2
0
Inventory
300
Regular
600
3
—
20
300
6
—
23
100
29
1000
100
34
100
37
500
Subcontract
28
31
34
Subcontract
Regular
23
—
26
1200
25
28
150
31
150
28
31
—
1300
Overtime
200
Regular
250
—
23
25
—
28
500
1300
Overtime
200
Subcontract
500
Demand
900
1500
1600
34
20
28
Subcontract
4
—
31
20
300
26
28
1200
Capacity
9
—
25
Regular
Unused
Capacity
4
Overtime
Overtime
3
3
3000
250
500
1300
200
31
500
20
1300
25
200
28
500
250
18
Burruss’ Production Plan
REGULAR
SUBENDING
PERIOD DEMAND PRODUCTION OVERTIME CONTRACT INVENTORY
1
2
3
4
Total
900
1500
1600
3000
7000
1000
1200
1300
1300
4800
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100
150
200
200
650
0
250
500
500
1250
500
600
1000
0
2100
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Other Quantitative Techniques
 Linear decision rule (LDR)
 Search decision rule (SDR)
 Management coefficients model
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Hierarchical Nature of Planning
Production
Planning
Capacity
Planning
Resource
Level
Product lines
or families
Aggregate
production
plan
Resource
requirements
plan
Plants
Individual
products
Master
production
schedule
Rough-cut
capacity
plan
Critical
work
centers
Components
Material
requirements
plan
Capacity
requirements
plan
All
work
centers
Manufacturing
operations
Shop
floor
schedule
Input/
output
control
Individual
machines
Items
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Available-to-Promise (ATP)
 Quantity of items that can be
promised to the customer
 Difference between planned
production and customer orders
already received
AT in period 1 = (On-hand quantity + MPS in period 1) –
- (CO until the next period of planned production)
ATP in period n = (MPS in period n) –
- (CO until the next period of planned production)
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ATP: Example
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ATP: Example (cont.)
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ATP: Example (cont.)
Take excess units from April
ATP in April = (10+100) – 70 = 40 = 30
ATP in May = 100 – 110 = -10
=0
ATP in June = 100 – 50 = 50
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Rule Based ATP
Product
Request
Yes
Is the product
available at
this location?
No
Availableto-promise
Yes
Is an alternative
product available
at this location?
No
Allocate
inventory
Yes
Is this product
available at a
different
location?
No
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Is an alternative
product available
at an alternate
location?
Yes
No
Allocate
inventory
Capable-topromise date
Is the customer
willing to wait for
the product?
No
Availableto-promise
Yes
Revise master
schedule
Trigger production
Lose sale
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Aggregate Planning for Services
Most services can’t be inventoried
Demand for services is difficult to predict
Capacity is also difficult to predict
Service capacity must be provided at the
appropriate place and time
5. Labor is usually the most constraining
resource for services
1.
2.
3.
4.
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Yield Management
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Yield Management (cont.)
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Yield Management: Example
NO-SHOWS
PROBABILITY
P(N < X)
0
1
2
3
.15
.25
.30
.30
.00
.15
.40
.70
.517
Optimal probability of no-shows
Cu
75
P(n < x) 
=
= .517
Cu + Co
75 + 70
Hotel should be overbooked by two rooms
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Copyright 2006 John Wiley & Sons, Inc.
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