© 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle...

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© 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

Transcript of © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle...

Page 1: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-1

Chapter 10Managing Economies of Scale in the

Supply Chain: Cycle Inventory

Supply Chain Management(3rd Edition)

Page 2: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-2

Outline

Role of Cycle Inventory in a Supply Chain Economies of Scale to Exploit Fixed Costs Economies of Scale to Exploit Quantity Discounts Short-Term Discounting: Trade Promotions Managing Multi-Echelon Cycle Inventory Estimating Cycle Inventory-Related Costs in

Practice

Page 3: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-3

Role of Inventory in the Supply Chain

Improve Matching of Supplyand Demand

Improved Forecasting

Reduce Material Flow Time

Reduce Waiting Time

Reduce Buffer Inventory

Economies of ScaleSupply / Demand

VariabilitySeasonal

Variability

Cycle Inventory Safety InventoryFigure Error! No text of

Seasonal Inventory

Page 4: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-4

Role of Cycle Inventoryin a Supply Chain

Lot, or batch size: quantity that a supply chain stage either produces or orders at a given time

Cycle inventory: average inventory that builds up in the supply chain because a supply chain stage either produces or purchases in lots that are larger than those demanded by the customer– Q = lot or batch size of an order– D = demand per unit time

Cycle inventory = Q/2 (depends directly on lot size)

Average flow time = Avg inventory / Avg flow rateAverage flow time from cycle inventory = Q/(2D)

Page 5: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-5

An Inventory System

D

D

Average Inv. Level

Page 6: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-6

Role of Cycle Inventoryin a Supply Chain

Q = 1000 unitsD = 100 units/dayCycle inventory = Q/2 = 1000/2 = 500 = Avg inventory level from

cycle inventoryAvg flow time = Q/2D = 1000/(2)(100) = 5 days Cycle inventory adds 5 days to the time a unit spends in the

supply chain Lower cycle inventory is better because:

– Average flow time is lower– Working capital requirements are lower– Lower inventory holding costs

Page 7: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-7

Role of Cycle Inventoryin a Supply Chain

Cycle inventory is held primarily to take advantage of economies of scale in the supply chain

Supply chain costs influenced by lot size:– Material cost = C– Fixed ordering cost = S– Holding cost = H = hC (h = cost of holding $1 in inventory for one year)

Primary role of cycle inventory is to allow different stages to purchase product in lot sizes that minimize the sum of material, ordering, and holding costs

Ideally, cycle inventory decisions should consider costs across the entire supply chain, but in practice, each stage generally makes its own supply chain decisions – increases total cycle inventory and total costs in the supply chain

Page 8: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-8

Economies of Scaleto Exploit Fixed Costs

How do you decide whether to go shopping at a convenience store or at Sam’s Club?

Lot sizing for a single product (EOQ) Aggregating multiple products in a single order Lot sizing with multiple products or customers

– Lots are ordered and delivered independently for each product

– Lots are ordered and delivered jointly for all products

– Lots are ordered and delivered jointly for a subset of products

Page 9: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-9

Economies of Scaleto Exploit Fixed Costs

Annual demand = D

Number of orders per year = D/Q

Annual material cost = CD

Annual order cost = (D/Q)S

Annual holding cost = (Q/2)H = (Q/2)hC

Total annual cost = TC = CD + (D/Q)S + (Q/2)hC

Figure 10.2 shows variation in different costs for different lot sizes

Page 10: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-10

Fixed Costs: Optimal Lot Sizeand Reorder Interval (EOQ)

D: Annual demand S: Setup or Order CostC: Cost per unith: Holding cost per year as a

fraction of product costH: Holding cost per unit per yearQ: Lot SizeT: Reorder intervalMaterial cost is constant and

therefore is not considered in this model

S

DHQDn

H

DSQ

hCH

2/*

2*

*

Page 11: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-11

Example 10.1

Demand, D = 12,000 computers per year

d = 1000 computers/month

Unit cost, C = $500

Holding cost fraction, h = 0.2

Fixed cost, S = $4,000/order

Q* = Sqrt[(2)(12000)(4000)/(0.2)(500)] = 980 computers

Cycle inventory = Q/2 = 490

Flow time = Q/2d = 980/(2)(1000) = 0.49 month

Reorder interval, T = 0.98 month

Page 12: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-12

Example 10.1 (continued)

Annual ordering and holding cost = = (12000/980)(4000) + (980/2)(0.2)(500) = $97,980Suppose lot size is reduced to Q=200, which would

reduce flow time:Annual ordering and holding cost = = (12000/200)(4000) + (200/2)(0.2)(500) = $250,000To make it economically feasible to reduce lot size, the

fixed cost associated with each lot would have to be reduced

Page 13: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-13

Example 10.2

If desired lot size = Q* = 200 units, what would S haveto be?

D = 12000 units

C = $500

h = 0.2

Use EOQ equation and solve for S:

S = [hC(Q*)2]/2D = [(0.2)(500)(200)2]/(2)(12000) = $166.67

To reduce optimal lot size by a factor of k, the fixed order cost must be reduced by a factor of k2

Page 14: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-14

Key Points from EOQ Model

In deciding the optimal lot size, the tradeoff is between setup (order) cost and holding cost.

If demand increases by a factor of 4, it is optimal to increase batch size by a factor of 2 and produce (order) twice as often. Flow time should decrease as demand increases.

If lot size is to be reduced, one has to reduce fixed order cost. To reduce lot size by a factor of 2, order cost has to be reduced by a factor of 4.

Page 15: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-15

Aggregating Multiple Productsin a Single Order

Transportation is a significant contributor to the fixed cost per order Can possibly combine shipments of different products from the same supplier

– same overall fixed cost– shared over more than one product– effective fixed cost is reduced for each product– lot size for each product can be reduced

Can also have a single delivery coming from multiple suppliers or a single truck delivering to multiple retailers

Aggregating across products, retailers, or suppliers in a single order allows for a reduction in lot size for individual products because fixed ordering and transportation costs are now spread across multiple products, retailers, or suppliers

Page 16: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-16

Example: Aggregating Multiple Products in a Single Order

Suppose there are 4 computer products in the previous example: Deskpro, Litepro, Medpro, and Heavpro

Assume demand for each is 1000 units per month If each product is ordered separately:

– Q* = 980 units for each product– Total cycle inventory = 4(Q/2) = (4)(980)/2 = 1960 units

Aggregate orders of all four products:– Combined Q* = 1960 units– For each product: Q* = 1960/4 = 490– Cycle inventory for each product is reduced to 490/2 = 245– Total cycle inventory = 1960/2 = 980 units– Average flow time, inventory holding costs will be reduced

Page 17: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-17

Lot Sizing with MultipleProducts or Customers

In practice, the fixed ordering cost is dependent at least in part on the variety associated with an order of multiple models– A portion of the cost is related to transportation (independent of

variety)– A portion of the cost is related to loading and receiving (not

independent of variety) Three scenarios:

– Lots are ordered and delivered independently for each product– Lots are ordered and delivered jointly for all three models– Lots are ordered and delivered jointly for a selected subset of

models

Page 18: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-18

Lot Sizing with Multiple Products

Demand per year– DL = 12,000; DM = 1,200; DH = 120

Common transportation cost, S = $4,000 Product specific order cost

– sL = $1,000; sM = $1,000; sH = $1,000

Holding cost, h = 0.2 Unit cost

– CL = $500; CM = $500; CH = $500

Page 19: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-19

Delivery Options

No Aggregation: Each product ordered separately

Complete Aggregation: All products delivered on

each truck

Tailored Aggregation: Selected subsets of products

on each truck

Page 20: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-20

No Aggregation: Order Each Product Independently

Litepro Medpro Heavypro

Demand per year

12,000 1,200 120

Fixed cost / order

$5,000 $5,000 $5,000

Optimal order size

1,095 346 110

Order frequency

11.0 / year 3.5 / year 1.1 / year

Annual cost $109,544 $34,642 $10,954

Total cost = $155,140

Page 21: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-21

Complete Aggregation: Order All Products Jointly

S* = S + sL + sM + sH = 4000+1000+1000+1000 = $7000

n* = Sqrt[(DLhCL+ DMhCM+ DHhCH)/2S*]

= 9.75

QL = DL/n* = 12000/9.75 = 1230

QM = DM/n* = 1200/9.75 = 123

QH = DH/n* = 120/9.75 = 12.3

Cycle inventory = Q/2

Average flow time = (Q/2)/(weekly demand)

Page 22: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-22

Complete Aggregation:Order All Products Jointly

Litepro Medpro Heavypro

Demand peryear

12,000 1,200 120

Orderfrequency

9.75/year 9.75/year 9.75/year

Optimalorder size

1,230 123 12.3

Annualholding cost

$61,512 $6,151 $615

Annual order cost = 9.75 × $7,000 = $68,250Annual total cost = $136,528 (No aggragation cost is $155,140)

Page 23: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-23

Tailored Aggregation: An Heuristic Approach

Which products should be ordered jointly?– Identify the product which is ordered most frequently.

– For each successive product i, identify the frequency mi, where product i is ordered every mi deliveries, i=1,2,...,n.

Not necessarily optimal, but close to optimal!

Given:– Di , Ci , S, si.

Page 24: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-24

Algorithm:

Step 1: Assuming independent ordering, find the most frequently ordered product

Step 2: Calculate the order frequency of each product as a multiple of .

and

)(2 i

iii sS

DhCn

},...,2,1|{ ninMaxn i

n

i

iii

s

DhCn

2 ii nnm ii mm

Page 25: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-25

Algorithm (cont’d.)

Step 3: Recalculate the ordering frequency of the most frequently ordered product,

Most frequently ordered product is ordered each time. Others are ordered in every mi orders, so their contribution to fixed cost of order is .

Step 4: For each product evaluate an order frequency

)(2

ii

iii

msS

DChn

ii ms

ii mnn

Page 26: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-26

Example: Best Buy Co.

S=$4,000, sL = sM = sH = $1000

DL = 12,000; DM = 1,200; DH = 120

Step 1: Calculate most frequently ordered model

Step 2: Calculate the frequency of M and H.

11)(2

L

LLL

sS

DhCn 11n1.1,5.3 HM nn

4.27.72

H

M

MMM n

s

DhCn

4.17.7/11 MM nnm

5Lm

2Mm

5.4Hm

Page 27: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-27

Example: Best Buy Co.

Step 3: Recalculate the ordering frequency of the most frequently ordered model L.

Step 4: Recalculate the frequency of M and H.

)(8.10)(2 L

ii

iii nmsS

DChn

year/16.25/8.10

year/4.52/8.10

HH

MM

mnn

mnn

Page 28: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-28

Tailored Aggregation:Order Some Products Jointly

Litepro Medpro Heavypro

Demand per year 12,000 1,200 120

Order frequency 10.8/year 5.4/year 2.16/year

Optimal order size

1,111 222 56

Cycle inventory 555.5 111 28

Annual holding cost

$55,556 $11,111 $2778

Average flow time

2.41 weeks 4.81 weeks 12.04 weeks

Annual order cost = Annual holding cost=$69,444Annual total cost = $131,004 (4% reduction in complete aggregation cost.)

560,61$ HHMMLL snsnsnnS

Page 29: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-29

Lessons from Aggregation

Aggregation allows firm to lower lot size without increasing cost

Complete aggregation is effective if product specific fixed cost is a small fraction of joint fixed cost

Tailored aggregation is effective if product specific fixed cost is a large fraction of joint fixed cost

Page 30: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-30

Quantity Discounts

What happens if the material cost, C is not a constant?Types of discounts: Lot size based (quantity purchased in a single order)

– All units quantity discounts– Marginal unit quantity discounts

Volume based (quantity purchased in a period)Questions: How should buyer react to maximize profit? How is the SC affected? Lotsizes, cycle inventories, flow

times, etc. When is it appropriate for the supplier to offer discounts?

What are appropriate discounting schemes?

Page 31: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-31

All-Unit Quantity Discounts

The unit cost generally decreases as the quantity increases, i.e., C0>C1>…>Cr

The objective for the company (a retailer in our example) is to decide on a lot size that will minimize the sum of material, order, and holding costs

322

211

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priceUnit

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qqqc

qqc

Page 32: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-32

Costs of Quantity Discounts Model

Total Cost

Order quantity,q

qC

qC

110

1100priceUnit

1

0

Page 33: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-33

All-Unit Quantity Discount Procedure (different from what is in the textbook)

Step 1: Calculate the EOQ for the lowest price. If it is feasible (i.e., this order quantity is in the range for that price), then stop. This is the optimal lot size. Calculate TC for this lot size.

Step 2: If the EOQ is not feasible, calculate the TC for this price and the smallest quantity for that price.

Step 3: Calculate the EOQ for the next lowest price. If it is feasible, stop and calculate the TC for that quantity and price.

Step 4: Compare the TC for Steps 2 and 3. Choose the quantity corresponding to the lowest TC.

Step 5: If the EOQ in Step 3 is not feasible, repeat Steps 2, 3, and 4 until a feasible EOQ is found.

Page 34: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-34

All-Unit Quantity Discounts: Example

Cost/Unit

$3$2.96

$2.92

Order Quantity

5,000 10,000

Order Quantity

5,000 10,000

Total Material Cost

Page 35: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-35

All-Unit Quantity Discount: Example

Order quantity Unit Price

0-5000 $3.00

5001-10000 $2.96

Over 10000 $2.92

q0 = 0, q1 = 5000, q2 = 10000

C0 = $3.00, C1 = $2.96, C2 = $2.92

D = 120000 units/year, S = $100/lot, h = 0.2

Page 36: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-36

All-Unit Quantity Discount: Example

Step 1: Calculate Q2* = Sqrt[(2DS)/hC2] = Sqrt[(2)(120000)(100)/(0.2)(2.92)] = 6410 bottlesNot feasible (6410 < 10001)Calculate TC2 using C2 = $2.92 and q2 = 10001TC2 = (120000/10001)(100)+(10001/2)(0.2)(2.92)+(120000)(2.92)= $354,520Step 2: Calculate Q1* = Sqrt[(2DS)/hC1]=Sqrt[(2)(120000)(100)/(0.2)(2.96)] = 6367 bottlesFeasible (5000<6367<10000) StopTC1 = (120000/6367)(100)+(6367/2)(0.2)(2.96)+(120000)(2.96)= $358,969Step 4: TC2 < TC1 The optimal order quantity Q* is 10001

Page 37: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-37

Notes on All-Unit Quantity Discounts

What is the effect of such a discount schedule?– Retailers are encouraged to increase the size of their orders

(optimal order quantity increases to 10,001 bottles from 6,324 bottles)– Average flow time is increased– Average inventory (cycle inventory) in the supply chain is increased

Is an all-unit quantity discount an advantage in the supply chain?

Suppose fixed order cost were reduced to $4 (from $100)– Without discount, Q* would be reduced to 1265 units from 6,324 bottles– With discount, optimal lot size would still be 10001 units– Quantity discount leads to 8 times increase in average inventory as well as

flow time !!!!

The impact is magnified if the fixed cost is smaller!

Page 38: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-38

Marginal-Unit Quantity Discounts

Cost/Unit

$3$2.96

$2.92

Order Quantity

5,000 10,000

Order Quantity

5,000 10,000

Total Material Cost

Page 39: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-39

Marginal-Unit Quantity Discounts

Also have been referred to as multiple-tariffs. It is not the average cost but the marginal cost per unit that

decreases at a breakpoint, Let be the cost of ordering units,

and Q be the order quantity,

,,...,, 10 rqqqiViq 00 V

)(...)()( 11121010 iiii qqCqqCqqCV

])([2/])([Cost Total

Cost Material TotalCost Holding Total

costorder Total

iiiiii CqQV

Q

DhCqQVS

Q

D

Page 40: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-40

Marginal-Unit Quantity Discounts

If then,

Otherwise, the optimal solution is in another range.

i

iiiii hC

CqVSDQC

)(2 pricefor sizelot Optimal

1 iii qQq

])([2/])([ iiii

iiiii

ii CqQV

Q

DhCqQVS

Q

DMinTC

Page 41: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-41

Marginal-Unit Quantity Discount: Example: Drugs on line

Ex: DO, Online retailer of prescription drugs and health supplements

Order quantity Marginal Unit Price

0-5000 $3.00 (C0)

5001-10000 $2.96 (C1)

Over 10000 $2.92 (C2)

D = 120000 units/year, S = $100, h = 0.2 $/$/year

Page 42: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-42

Marginal-Unit Quantity Discount: Example: Drugs on line

800,29$)000,5000,10(96,2)05000(3

000,15$)05000(3,0

92.2,96.2,3

000,10,5000,0

2

10

210

210

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VV

CCC

qqq

feasible961,16)(2

feasiblenot 028,11)(2

feasiblenot 324,6)(2

2

2222

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1111

0

0000

hC

CqVSDQ

hC

CqVSDQ

hC

CqVSDQ

365,360$])([2/])( 22222

22222

2

CqQV

Q

DhCqQVS

Q

DMinTC

Page 43: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-43

Notes on Marginal-Unit Quantity Discount

Lot size is increased to 16,961 from 6,324 by offering a marginal unit quantity discount.

Is a marginal-unit quantity discount an advantage in the supply chain?

If the fixed order cost is $4 (instead of $100), the optimal lot size for DO is 15,755 (with the discount), compared to 1,265 (without the discount).

The impact on lot size is magnified if the fixed cost is smaller!

Page 44: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-44

Why Quantity Discounts?

Improved coordination in the supply chainA SC is coordinated if both the manufacturer and the retailer make decisions to maximize SC profits.

How can a manufacturer use appropriate quantity discounts to ensure that coordination is achieved even if the retailer is acting to maximize its own profits given its cost structure?

Extraction of surplus through price discriminationSC has multiple retailers each with different demand structure all supplied by a single manufacturer. Firm charges different prices to maximize profits.Ex:Passengers travelling on the same plane often pay different prices.

What is the form of discount scheme to be offered?

Page 45: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-45

Quantity Discounts forCommodity Products

D = 120,000 bottles/year SR = $100, hR = 0.2, CR = $3 Lot Size =6,324

SM = $250, hM = 0.2, CM = $2

Supply chain cost = $9,804

Retailer Manufacturer

Holding Cost $1,897 $1,265

Order Cost $1,898 $4,744

Total Cost $3,795 $6,009

Page 46: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-46

Quantity Discounts forCommodity Products

What can the supplier do to decrease supply chain costs?Coordinated lot size: 9,165

– Retailer cost = $4,059 Supply chain cost

= $9,165

– Manufacturer cost = $5,106

)))32(*2,0/(000,120)250100(2(

638

264

902

Page 47: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-47

Pricing Schemes for Coordination: Commodity Products

Effective pricing schemes– Marketing can offer all-unit quantity discount

» $3 for lots below 9,165

» $2.71 for lots of 9,165 or more

– Manufacturing pass some fixed cost to retailer (enough that he raises order size from 6,324 to 9,165)

Optimal lot size forretailer is 9165

Page 48: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-48

Key Notes for Quantity Discounts in Commodity Products

For commodity products where price is set by the market, lot size based quantity discount is appropriate to achieve coordination.

However lot size based discount increases cycle inventory.

Often firms find that significant efforts to reduce order costs do not reduce inventory in the SC because of quantity discounts, so coordination is required! So as the manufacturer lowers his setup cost, the discount he offers to retailers should change!

Page 49: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-49

Quantity Discounts WhenFirm Has Market Power

Manufacturer invents a new vitamin pill. Few or no competitors! Demand curve faced by DO is affected by the price as

360,000 - 60,000p What are the optimal prices and profits in the following situations if CM =

$2/bottle?

– The two stages make the pricing decision independently

» Price of manufacturer= CR = $4/bottle,

» Price of DO=p=$5/bottle Demand = 60,000

» Profit = PM+PR=$120,000+ $60,000=$180,000

RR Cppp )000,60000,360()000,60000,360(Profit

MRRRM CCCC )000,30000,180()000,30000,180(Profit

Page 50: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-50

Quantity Discounts WhenFirm Has Market Power

– The two stages coordinate the pricing decision» p = $4, CR=2, Demand = 120,000 bottles,

» Profit = PM+PR=0+240,000 = $240,000 ($60,000 higher.)

– The SC profit is lower if each stage of the SC independently takes its pricing decisions with the objective of maximizing its own profit!

M R

CR pCM

Page 51: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-51

Pricing Schemes for Coordination: Firm has Market Power

Retailer DO acts in a way to maximize its own profits.

Design a two-part tariff that achieves the coordinated solution

Design a volume discount scheme that achieves the coordinated solution

Impact of inventory costs– Pass on some fixed costs with above pricing

Page 52: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-52

Two Part Tariff

Manufacturer charges his entire profit as an up-front franchise fee and then sells the retailer at cost. It is then optimal for the retailer to price as though the two stages are coordinated.

Ex: With coordination SC Profit=$240,000

Without Coordination PR=$60,000

Manufacturer charges up-front fee of $180,000 and set CR=2.

Retailer maximizes PR when p=$4/bottle

and his net profit is $240,000-$180,000=$60,000.

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Volume Based Quantity Discount Two part tariff is actually a volume based quantity discount. Here the objective is to price in a way that the retailer buys the total volume

sold as if the two stages coordinate pricing.

Ex: With coordination demand=$120,000 bottles /year.

Manufacturer offers

Then it is optimal for DO to order 120,000 units at set p=$4/unit.

So, PR= $60,000, PM= $180,000 and SC Profit=$240,000.

120,000quantity purchaseyearly if$3.5

120,000quantity purchaseyearly if$4RC

Page 54: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Lessons from Discounting Schemes For commodity products, lot size based discounts are justified

to achieve coordination. For the products where a firm has market power, lot size based

discounts are not optimal even in the presence of inventory costs. Volume based discounts with some fixed cost passed on to retailer are more effective.

Lot size based discounts tend to raise the cycle inventory in the SC. Volume based discounts are compatible with small lots.

Hockey-stick phenomenon: In volume based discounts, orders peak toward the end of the financial horizon. Solution is to base the volume discounts on a rolling horizon.Ex: Manufacturer may offer DO volume discount based on the sales during the last 12 months.

Page 55: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Price Discrimination to Maximize Supplier Profits

Ex: Quantity purchased by DO=200,000-50,000 CR.

Optimally CR=$3 where CM=$2. Optimal PM= $50,000.

Price

Demand

4

Marginal cost=$2

200,000

Consumer surplus at a price of $3

Welfare loss with uniform price of $33

2

Page 56: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Short-Term Discounting: Trade Promotions

Trade promotions are price discounts for a limited period of time (also may require specific actions from retailers, such as displays, advertising, etc.)

Key goals for promotions from a manufacturer’s perspective:– Induce retailers to use price discounts, displays, advertising to increase sales– Shift inventory from the manufacturer to the retailer and customer– Defend a brand against competition– Goals are not always achieved by a trade promotion

What is the impact on the behavior of the retailer and on the performance of the supply chain?

Retailer has two primary options in response to a promotion:– Pass through some or all of the promotion to customers to spur sales– Purchase in greater quantity during promotion period to take advantage of temporary

price reduction, but pass through very little of savings to customers

Page 57: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education 10-57

Short Term Discounting

Q*: Normal order quantity

C: Normal unit cost

d: Short term discount

D: Annual demand

h: Cost of holding $1 per year

Qd: Short term order quantity

Qd can not exceed the demand during discount period, Q1!

dC

C

hdC

dD QQ

d

-+

)-(=

*

Forward buy = Qd - Q*

Qd Min{Qd, Q1}

Page 58: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

© 2007 Pearson Education

Short Term Discounting: Trade Promotions

10-58

Qd

Q*

t

I(t)

Page 59: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Short Term Discounts:Forward Buying

Normal order size, Q* = 6,324 bottles

Normal cost, C = $3 per bottle

Discount per tube, d = $0.15

Annual demand, D = 120,000

Holding cost, h = 0.2

Forward buy = Qd - Q*=38,236 - 6,324=31,912 bottles

236,3815.03

324,63+

20.0)15.03(

000,12015.0=

Q

d

Page 60: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Promotion Pass Throughto Consumers

Demand curve at retailer: 300,000 - 60,000p

Normal supplier price, CR = $3.00– Optimal retail price = $4.00

– Customer demand = 60,000

Promotion discount = $0.15– Optimal retail price = $3.925

– Customer demand = 64,500

Retailer only passes through half the promotion discount and demand increases by only 7.5%

Page 61: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Weekly Consumption ofChicken Noodle Soup

0

50

100

150

200

250

300

350

Consumption

Page 62: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Weekly Shipments ofChicken Noodle Soup

0

100

200

300

400

500

600

700

800

ShipmentsConsumption

Page 63: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Trade Promotions

When a manufacturer offers a promotion, the goal for the manufacturer is to take actions (countermeasures) to discourage forward buying in the supply chain.

Counter measures– EDLP: Every day low price

– More convenient when there is high deal elasticity and high inventory holding costs at the retailer.

– Scan based promotions: Discount applied to sell through, rather than sell in.

– Customer coupons: Limited allocation to retailers based on previous sales

Page 64: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Managing Multi-EchelonCycle Inventory

Multi-echelon supply chains have multiple stages, with possibly many players at each stage and one stage supplying another stage

The goal is to synchronize lot sizes at different stages in a way that no unnecessary cycle inventory is carried at any stage

Figure 10.6: Inventory profile at retailer and manufacturer with no synchronization

Figure 10.7: Illustration of integer replenishment policy Figure 10.8: An example of a multi-echelon distribution

supply chain In general, each stage should attempt to coordinate orders

from customers who order less frequently and cross-dock all such orders. Some of the orders from customers that order more frequently should also be cross-docked.

Page 65: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Estimating Cycle Inventory-Related Costs in Practice

Inventory holding cost– Cost of capital– Obsolescence cost– Handling cost– Occupancy cost– Miscellaneous costs

Order cost– Buyer time– Transportation costs– Receiving costs– Other costs

Page 66: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Levers to Reduce Lot Sizes Without Hurting Costs

Cycle Inventory Reduction– Reduce transfer and production lot sizes

» Aggregate fixed costs across multiple products, supply points, or delivery points

– Are quantity discounts consistent with manufacturing and logistics operations?

» Volume discounts on rolling horizon

» Two-part tariff

– Are trade promotions essential?» EDLP

» Based on sell-thru rather than sell-in

Page 67: © 2007 Pearson Education 10-1 Chapter 10 Managing Economies of Scale in the Supply Chain: Cycle Inventory Supply Chain Management (3rd Edition)

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Summary of Learning Objectives

How are the appropriate costs balanced to choose the optimal amount of cycle inventory in the supply chain?

What are the effects of quantity discounts on lot size and cycle inventory?

What are appropriate discounting schemes for the supply chain, taking into account cycle inventory?

What are the effects of trade promotions on lot size and cycle inventory?

What are managerial levers that can reduce lot size and cycle inventory without increasing costs?