Week 4: The Bullwhip Effect

1
Week 4The Bullwhip Effect

• MIS 3580 Internet-Enabled Supply Chains
• Prof. Sunil Wattal

2
Learning Objectives

• Understand the bullwhip effect
• Learn what causes the effect
• Learn ways to counteract the bullwhip
• Have some fun with the beer game

3
The Pampers problem

• Pampers a PG products
• Mild fluctuations in retail sales excessive
  fluctuations at distributor level
• The orders of materials to the Pampers
  suppliers, eg 3M, fluctuated even more
• Yet, Pampers were consumed at the same steady
  rate
• What explains the variability?

4
At Hewlett-Packard

• Similar problem at HP major printer
  manufacturer

5
Fluctuations at HP

• Some fluctuations at retailer level
  understandable
• More fluctuations at reseller level
• Much greater fluctuations in the manufacturing
  divisions orders to the IC division

6
Fluctuations along the chain
7
Fluctuations along the chain

• Consumer sales are relatively stable
• The retailers orders show more variability
• The wholesalers orders show even more
  variability
• The manufacturers orders show much greater
  fluctuations

8
The bullwhip effect

• Distorted information from one end of the supply
  chain to another creates a fluctuation in the way
  the various entities behave
• The resulting variability in forecasts, orders
  and inventory levels is called the bullwhip
  effect

9
Learning Objectives

• Understand the bullwhip effect
• Learn what causes the effect
• Learn ways to counteract the bullwhip
• Have some fun with the beer game

10
What causes the bullwhip effect?

• Demand forecast updating
• Order batching
• Price fluctuation
• Rationing and shortage gaming

11
Demand forecast updating

• Forecasts are generally made using the
  exponential smoothing technique
• At each level in the supply chain, the input to
  the demand forecast is the orders from one level
  below in the supply chain
• As orders from the level below keep changing, so
  does your forecast
• Your forecast is the input to the forecast of the
  entity one level above
• As your forecasts vary, their forecasts vary even
  more

12
Order batching

• A retailer orders products in batches
• When demand comes in, the retailer does not order
  immediately, but accumulates demand and then
  orders again in batches
• This causes a constant ebb and flow

13
Price fluctuation

• On average, 80 of transactions in the grocery
  industry is forward buy
• Forward buying results in price fluctuations
• Also, there are price discounts, quantity
  discounts, coupons, rebates etc
• Hence customers buy in quantities that doesnt
  reflect immediate needs
• How often have you bought an extra box of corn
  flakes or an extra bottle of juice because of a
  temporary price reduction?

14
Rationing and Shortage Gaming

• Scenario Demand exceeds supply
• Manufacturer can ration product supply
• If total supply is only 50 of total demand,
  customers will receive only 50 of their order
• Knowing this, customers exaggerate their real
  needs when they order
• When demand cools, orders get cancelled
• Examples Sales of DRAM chips in the 1980s
  disappearance of HP Laserjet orders

15
Learning Objectives

• Understand the bullwhip effect
• Learn what causes the effect
• Learn ways to counteract the bullwhip
• Have some fun with the beer game

16
Counteracting the bullwhip

• Avoid multiple demand update forecasts
• Break order batches
• Stabilize prices
• Eliminate gaming in shortage situations

17
Avoid multiple demand order forecasts

• What causes multiple demand order forecasts?
• Forecast from one entity becomes input for
  higher-level entity
• Simply put, different entities in the supply
  chain work with different demand data
• To counteract
• Share data
• Create demand forecasts using same raw data

18
Avoid multiple forecasts (contd.)

• Tools techniques
• Use point-of-sale data
• The actual sale data becomes the raw data for
  forecast updates along the system
• Electronic Data Interchange / Internet
• EDI or Internet web services ensures that the
  same data is shared across multiple entities at
  frequent intervals
• Computer-assisted ordering

19
Break order batches

• Orders involve paperwork and red tape
• Also companies offer differential pricing between
  full-truckload and less-than-truckload
  transportation
• How to counteract?
• EDI
• Truckloads with different products

20
Stabilize prices

• Problem
• Forward buying leads to price fluctuations
• Price discounting leads to uneven demand patterns
• How to counteract?
• Reduce frequency and level of wholesale price
  discounting
• Everyday Low Price / Value pricing strategy

21
Eliminate shortage gaming

• Problem
• Demand exceeds supply
• Suppliers order more to counteract lower supply
• How to counteract?
• Do no allocate products on the basis of orders
  alone
• Allocate in proportion to past sales records

22
Eliminate shortage gaming (contd.)

• Information sharing
• Shortage gaming arises due to lack of trust
• Sharing information can help overcome this
• Stop generous return policies!
• Penalties for returns to manufacturers this
  ensures that retailers will not exaggerate needs,
  and later cancel orders

23
Summary
24
Learning Objectives

• Understand the bullwhip effect
• Learn what causes the effect
• Learn ways to counteract the bullwhip
• Have some fun with the beer game

25
The beer game

• Originally conceived at MIT
• A very good exercise in understanding the
  bullwhip effect
• The rules

26
Setting the context

• The picture shows a simplified beer supply chain
• The arrows show the direction in which the beer
  flows
• Demand information flows in the opposite direction

27
The rules of the game

• You, the player, can play one of the four roles
  you are the manager at the
• Retailer
• Wholesaler
• Distributor
• Factory
• The factory has access to unlimited amounts of
  raw materials, labor etc.

28
The rules (contd.)

• Each player has to work with the following
  parameters
• Order this is the order that you have received
  from the next level down your supply chain
• A retailers orders are dependent on the
  perceived demand a wholesalers order number is
  that which has been demanded by the retailer and
  so on.
• Inventory the numbers in stock
• Backlog unfulfilled orders from past week(s)

29
The rules (contd.)

• Inventory costs For every item in the inventory,
  the holding entity (retailer etc) is charged
  0.50
• Backorder costs For every item that is
  unfulfilled, the entity unable to fulfill the
  order is charged 1.00
• It takes two weeks for an order information to
  move one level up the supply chain

30
The rules (contd.)

• An example
• An order from the retailer reaches the wholesaler
  in week 2, the distributor in week 3, and the
  factory in week 4.
• Each entity tries to fulfill the order with the
  inventory on hand
• If not, it becomes a backlog
• It can take as many as 12 weeks to fulfill an
  order (retailer ? wholesaler ? distributor ?
  factory ? distributor ? wholesaler ? retailer)

31
The rules (contd.)

• The objective of the game
• To minimize the total supply chain cost (i.e.
  inventory costs backorder costs)
• Lets play the game!

32
Your thoughts

• Which role did you play?
• What were your individual costs? What was the
  total supply chain cost?
• Share your thoughts about the game
• What could have helped you bring down the costs?

33
Next week

• In class Beer Game