BEERGAMEINSTRUCTIONS System Dynamics Society Beer Game Instructions
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System Dynamics Society
Milne 300 - Rockefeller College
University at Albany - State University of New York
Albany, NY 12222
Phone (518) 442-3865 Fax (518) 442-3398 E-mail: System.Dynamics@albany.edu
http://www.albany.edu/cpr/sds/
Instructions for Running the Production-Distribution Game
“The Beer Game”
Adapted from Instructions written by John Sterman;
Revised by System Dynamics Society, May 1998
------------------------------------------------------------------------
This document outlines the protocol for the Production-Distribution Game (The Beer Game), developed
to introduce people to concepts of system dynamics. The game can be played by as few as four and as
many as 60 people (assistance is required for larger groups). The only prerequisite, besides basic math
skills, is that none of the participants have played the game before, or else agree not to reveal the "trick"
of the game.
1. Purpose
a. Introduce people to the key principle "structure produces behavior"
b. Experience the pressures of playing a role in a complex system
2. Overview of production-distribution system
a. Identify the four positions on the board: retailer, wholesaler, distributor, and factory. Each
board will have one or two players at each position. Each board comprises one team.
b. Each position is identical (except for the factory). Each position has an inventory of beer.
Each position receives orders from and ships beer to the sector downstream. Each
position orders beer from the sector upstream. Beer is received after a shipping delay. (In
the case of the factory, beer is received after a production delay.) Orders are received
after a mailing delay (orders placed to incoming orders).
3. Basic rules
a. Have each team pick a name for their brewery (e.g. the name of a real beer).* Distribute
one Record Sheet to each position and have them label their Record Sheet with the name
of their brewery and their position, e.g. retailer, wholesaler, etc.
b. Have each person ante up $1.00, or an appropriate amount, which will go to the winning
team, winner takes all.
*Note: The product represented by the chips does not have to be beer. Any product
appropriate to the group may be chosen by the facilitators.
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c. The object of the game is to minimize total costs for your team. The team with the lowest
total costs wins. Costs are computed in the following way: The carrying costs of
inventory are $.50 per case per week. Out-of-stock costs, or backlog costs, are $1.00 per
case per week. The costs of each stage (retailer, wholesaler, distributor, factory) for each
week, added up for the total length of the game, determine the total cost.
d. No communication between positions. Retailers should not talk to anyone else, same for
wholesalers, distributors, and factories. The reason for this is that in real life there may be
five factories, several dozen distributors, thousands of wholesalers, and tens of thousands
of retailers, and each one cannot find out what the total activity of all the others is. The
only communication between sectors should be through the passing of orders and the
receiving of beer.
e. Retailers are the only ones who know what the customers actually order. They should not
reveal this information to anyone else.
4. Steps of the Game (see attached sheet). The game leader should call out the steps as the
game progresses. The first few times when the system is still in equilibrium the leader should
go through the steps very slowly to make sure people have the mechanics down. Notice that
of the five steps of the game, only the last, placing orders, involves a decision. The first four
steps only involve moving inventory of beer or order slips, and are purely mechanical. For the
first few weeks the leader should tell everyone to order four units to keep the system in
equilibrium.
5. Initialization of the boards
a. There should be twelve chips (or coins) representing twelve cases of beer in each
inventory. Each chip or coin represents one case. There should be four chips in each
shipping box and production delay. There should be order slips with "4" written on them,
face down in each order box (orders placed, incoming orders, and production requests). A
supply of blank order slips should be available at each position (see Initializing The
Board sheet). A supply of chips should be placed at the factory for production of new
cases of beer.
b. Place the customer order cards in the “order cards” box, with the order numbers face
down, and the week number showing. Weeks 1 through 50 should be in order. The
customer order cards with the customer demand should not be revealed in advance. The
pattern of customer demand that is most effective for first-time players is a pattern of four
cases per week until week five, and then eight per week from week five on. Each order
deck should have fifty weeks' worth of cards, and the players should be told that the game
will be fifty weeks long. Typically it is only necessary to run the game thirty-five weeks
or so in order to see the pattern of fluctuation, but telling the players it will be fifty weeks
prevents horizon effects, where they run their inventories down because they feel the end
of the game is coming.
6. Tips
a. It is very helpful if the game leader makes sure that each team stays in step so that he/she
can quickly glance around the room and see that everyone is at the right place.
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b. The game leader should write the current week on the blackboard or flip chart as the steps
for that week are called out.
c. In about the eighth or ninth week the retailer will run out of inventory and have a backlog
for the first time. People do not understand the meaning of backlogs, or the cumulative
nature of the backlog. It is necessary to stop the game at this point, ask everyone to pay
attention, and explain how backlog accounting works. Explain that the backlog represents
orders you have received, but have not yet filled, and which you must fill in the future.
Explain that the backlog is cumulative. "Next week you have to fill the incoming orders
that you receive, plus whatever is in your backlog, if possible. If not possible, then the
amount left over is added to the existing backlog and must be filled in later weeks."
Emphasize at this point that backlog costs twice as much as inventory. You may need to
do this one or two more times, and should be careful to check and be sure that they do in
fact fill their backlog. It is helpful to write the following equation on the blackboard to
help with backlog accounting:
Orders to fill = New orders + Backlog
this week this week last week
(Please see “Orders to Fill” sheet)
d. The game can be played in as little as one and a half hours if the leader maintains a very
brisk pace. The debriefing usually requires at least 40 minutes and can be expanded
substantially.
The attached quotation from Tolstoy's War and Peace illustrates well the idea "structure
produces behavior.”
7. End of game
a. Halt the game after about 36 weeks (but play the game up to that point as if it is going on
to 50 weeks, to avoid unusual end-of-game moves).
b. Ask each position on each team to calculate their total cost :
Cost = Total Inventory X $0.50 + Total Backlog X $1
and to mark the total cost on the Record Sheet for the position.
c. Pass out Orders graph sheets - one to each position. Ask each position to graph their
own orders, week by week. Clarify to Factory that they will graph their Production
Requests.
d. Pass out Effective Inventory graph sheets - one to each position. Ask each position to
graph the inventory week by week, showing any backlog as negative inventory.
e. Team name and position must be indicated on all sheets. Once the graph is complete,
have the players connect the dots with a bold magic marker (color coded - black, blue,
green and red - to the board) for ease of viewing by the group.
f. Pass out the Customer Order graph sheets to everyone except Retailers. Ask each person
to sketch what he or she thinks the customer order rate looked like over time. Ask each to
indicate a simple scale or maximum value.
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Ask Retailers not to discuss anything about customer orders until after the
debrief of the game.
g. Collect all the sheets, and send players off for a break.
h. During break:
a) Calculate team costs to determine the winner, and compute the average team cost.
b) Tape sheets together (as shown below) and hang up team graphs.
Effective Inventory Orders/Production Requests
Retailer Retailer
Wholesaler Wholesaler
Distributor Distributor
Factory Factory
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Tolstoy on the "Laws of History"
War and Peace
Part 11, I:
"The first fifteen years of the nineteenth century present the spectacle of an extraordinary
movement of millions of men. Men leave their habitual pursuits; rush from one side of
Europe to the other; plunder, slaughter one another, triumph and despair; and the whole
current of life is transformed and presents a quickened activity, first moving at a growing
speed, and then slowly slackening again. What was the cause of that activity, or from
what laws did it arise? asked the human intellect.
The historians, in reply to that inquiry, lay before us the sayings and doings or some
dozens of men in one of the buildings of the city of Paris, summing up those doings and
sayings by one word--revolution. Then they give us a detailed biography of Napoleon,
and of certain persons favorably or hostilely disposed to him; talk of the influence of
some of these persons upon others; and then say that this it is to which that activity is due,
and these are its laws.
But the human intellect not only refuses to believe in that explanation, but flatly declares
that the method of explanation is not a correct one, because in this explanation a smaller
phenomenon is taken as the cause of a greater phenomenon. The sum of men's individual
wills produced both the revolution and Napoleon; and only the sum of those wills
endured them and then destroyed them.
‘But whenever there have been wars, there have been great military leaders; whenever
there have been revolutions in states, there have been great men,' says history. 'Whenever
there have been great military leaders there have, indeed, been wars,' replies the human
reason; 'but that does not prove that the generals were the cause of the wars, and that the
factors leading to warfare can be found in the personal activity of one man.'
...
For the investigation of the laws of history, we must completely change the subject of
observations, must let kings and ministers and generals alone, and study the
homogeneous, infinitesimal elements by which masses are led. No one can say how far it
has been given to man to advance in that direction in understanding of the laws of history.
But it is obvious that only in that direction lies any possibility of discovering historical
laws; and that the human intellect has hitherto not devoted to that method of research one
millionth part of the energy that historians have put into the description of the doings of
various kings, ministers, and generals...."
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OUTLINE FOR POST-GAME DISCUSSION
1. Get all the graph sheets of results (Orders, Effective Inventory) taped up for display.
2. Find out which team won (lowest total cost) and distribute the winnings.
3. Although they played the game to minimize cost, that is not the real purpose of the game.
The game is designed to:
1) give them an experience of playing a role in a system
2) show them how "structure produces behavior"
4. Ask participants what their experience of playing the game was. Some good leading questions
are:
1) Did you feel yourself "at the mercy" of forces in the system from time to time? Did you
feel the effects of the forces in the system from time to time? (i.e., relatively helpless in
the face of huge incoming orders or excess inventories)
2) Did you find yourself "blaming" the person next to you for your problems?
5. After a few minutes (about 10) of discussion, look at the graphs of the results. Ask them,
"What commonalities do you see in the graphs for the different teams?" Participants should
see common pattern of overshoot and oscillation. This should be most evident in the effective
inventory graph.
• Get them to really see for themselves that different people in the same structure produce
qualitatively similar results. Even though they acted very differently as individuals in
ordering inventory, still the overall patterns of behavior are similar.
Differences in individual ordering patterns (free will) result in the quantitative differences in
game results. But the qualitative patterns are the same.
• This is a very important point--take as long as necessary to have them see it for
themselves.
You might reflect at this point on what happens in the real world when such order-rate and
inventory oscillations are generated. The typical organizational response is to find the "person
responsible" (the guy placing the orders or the inventory manager) and blame him. The game
clearly demonstrates how inappropriate this response is--different people following different
decision rules for ordering all generated oscillations.
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6. After having had them all see the extent to which different people produce similar results in a
common structure, you then need to move on to what is usually the most powerful point made
by the game: that internal structure, not external events, cause system behavior. The way to
make this point is to ask the following question:
"All of you who were not retailers, or who otherwise have not found out what the pattern of
customer orders was, what do you think the customers were doing?"
Most people usually believe that customer demand was fluctuating because they believe that
the system fluctuations must have been externally driven. Get each of them (other than
retailers) to see that they assumed fluctuating customer orders.
• Show the Customer Order charts that were filled out at the end of the game (Sketch a few
on an single overhead transparency. Then go to one team’s graphs and carefully draw in
the customer order rate on the Factory’s Order (Production Requests) graph. The small
step from from 4 to 8 orders should make a strong visual impression in contrast to the
order rate fluctuations which often have an amplitude of 20 to 40 orders per week.
Moreover, the sustained oscillations generated by the system contrast sharply to the
absolutely flat customer order rate after the step at week 5.
This simple exercise of getting them to see how, contrary to their expectations, the internal
system structure is completely capable of generating fluctuating behavior is the most
profound lesson they can learn from the game.
• It is important that they see this for themselves, as a demonstration or an
experimental result which they did, not as an idea of which you are trying to
convince them. In fact, the game is an experiment in very true sense. The result of
oscillating behavior was not predetermined.
7. The assumption that the system's problems are caused by the customer stems from the
external orientation most of us adopt in dealing with most problems. In a sense, this is just an
extension of the viewpoint that attributes your problems to the person(s) playing next to you
in the game: "he/she did it to me" is a special case of "they (the customers) did it to me". In
system dynamics we take an alternative viewpoint--that the internal structure of a system is
more important than external events in generating qualitative
patterns of behavior. This can be illustrated by this diagram:
events
(such as inventory stock-outs
and extreme order surges)
behavior/process (oscillation)
structure
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Most people try to explain reality by showing how one set of events causes another or, if they
have studied a problem in more depth, by showing how a particular set of events are part of a
longer-term historical process.
• Have the participants illustrate this for themselves by looking at their own "explanations"
for events during the game. Take a particular incident in the game, for example a large
surge in production requests at the factory, and ask the people responsible why they did
that. Their answer will invariably relate their decision to some prior decision of the people
they supply or who supply them. Then turn to those people and ask them why they did that.
Continue this until people see that one can continue to relate one event to earlier events
indefinitely.
The basic problem with the "events cause events" orientation is that it gives you very little
power to alter the course of events. The focus on internal structure greatly enhances the
possibilities of influencing the course of events because you are dealing with the underlying
source of the process, not just trying to manipulate events.
The slinky demonstration on the training video is a good way to emphasize the
focus on internal structure -- the slinky oscillates not just because the hand was
withdrawn but mainly because there is something about the structure of a spring
that wants to oscillate. (Please note: This training video is currently in production
and not yet available.)
8. If time permits, have students think of examples of problems which can be viewed as
internally or externally caused.
e.g. illness
famine
9. This leaves you at the point of dealing with the problem:
"How do we deal more effectively with underlying structure?"
• This is the purpose of system dynamics. So you are in an excellent position to begin
introducing system dynamics tools for understanding underlying structure.
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STEPS OF THE GAME
------------------------------------------------------------------------
1. Receive inventory and advance the shipping delays.
Factory advance the production delay.
2. Look at incoming orders and fill orders. (Retailer looks at customer order cards.
Factory looks at incoming orders, not the production request.)
All incoming orders plus orders in backlog must be filled.
If your inventory is insufficient to fill incoming orders plus backlog, fill as many orders as
you can and add the remaining orders to your backlog.
3. Record your inventory or backlog.
4. Advance the order slips; and the brewery brews. That is, the factory converts the production
request from last week into cases of beer and put the cases (chips) in the first production
delay.
5. Place and record your orders. Factory places and records its production requests.
Beer Game Checklist
Project/Company: ______________________________________ Date: _______________
Per Team (or board)
ٱ Game board (1)
ٱ Single chips (500-600)
ٱ Ten chips (30) (optional, can replace some
single chips)
ٱ Customer order cards (1)
ٱ Order slips (200)
ٱ Graphs
- Effective Inventory (4)
- Orders (4)
- Customer Orders (3)
ٱ Record sheets (4)
ٱ Pencils (4)
ٱ Markers in four colors (1 each)
- Green - Blue
- Red - Black
ٱ Calculators (2)
Per Session
ٱ Masking tape
ٱ Outline for post-game discussion
ٱ Orders to Fill sheet
ٱ Flip charts (optional)
ٱ Slinky (optional)
ٱ Previous game graphs (if available)
What you receive with one complete set:
- Game board (1) - Video (1)
- Customer order cards (1) - Single chips (600)
- Printed instructions including record sheet, graphs, etc. to be duplicated
- Articles relating to the Beer Game
What you need to purchase/obtain to provide for game:
- Markers in four colors - Masking tape
- Pencils - Flip chart (if needed)
- Calculators - Slinky (optional)
What you need to duplicate/make for distribution:
Graphs: Copy:
1. Record Sheet (4 per team) - One per position
2. Effective Inventory graph (4 per team) - One per position
3. Orders graph (4 per team) - One per position
4. Customer Orders graph (3 per team) - One for wholesaler, distributor and factory only, not retailer.
Blank Order Slips
• 50 placed at each position
o You may use small “Post-it” notes, or cut paper into small rectangles measuring approximately 1.5”
x 2”
• Make seven order slips per game board with “4” on each one, and place them face down in each of the
“orders” boxes to initialize the game board.
Note: Order slips showing “4” are placed face down on the game board.
Customer order cards are placed in “Customer Orders” box.
Orders to Fill
1. Orders to fill = Backlog + Current
Orders
2. a) If you have enough inventory, ship all
the orders to ship and record your new
inventory.
2. b) If you do not have enough inventory,
ship all the inventory you have and
record the remaining unfilled orders to
fill as your new backlog.
may be duplicated as an overhead for instruction
Record Sheet
Please check-off your position:
Team Name: ___________________ ٱ Retailer ٱ Wholesaler ٱ Distributor ٱ Factory
Week Inventory Backlog Your Orders
Placed
Week Inventory Backlog Your Orders
Placed
1 26
2 27
3 28
4 29
5 30
6 31
7 32
8 33
9 34
10 35
11 36
12 37
13 38
14 39
15 40
16 41
17 42
18 43
19 44
20 45
21 46
22 47
23 48
24 49
25 50
Total:
INV 1 BL 1 INV 2 BL 2
(INV1 + INV2) X .50
+ (BL1 + BL2) X 1.00
= Total Cost
Effective Inventor
y
5 10 15 20 25 30 35
70 70
60 60
50 50
40 40
30 30
20 20
10 10
0
5
weeks
10
weeks
15
weeks
20
weeks
25
weeks
30
weeks
35
weeks 0
-10 -10
-20 -20
-30 -30
-40 -40
-50 -50
-60 -60
-70 5 10 15 20 25 30 35 -70
Team Name ________________________________________________ ;Please check off your position: Retailer Wholesaler Distributor Factory
Orders
(
and Production Re
q
uests for Factory
)
Team Name__________________________________________________;Please check off your position: Retailer Wholesaler Distributor Factory
5 10 15 20 25 30 35
60
50 50
40
40
30 30
20
20
10 10
8
6
4
2
1 2 3 4 5 weeks 10 weeks 15 weeks 20 weeks 25 weeks 30 weeks 35 weeks
Customer Orders Team:
(Sketch here what you think customer orders were)
Position:
ٱ Wholesaler
ٱ Distributor
ٱ Factory
(Retailers do not fill this in)
5 10 15 20 25 30 35
Week
The Beer Distribution Game
An Annotated Bibliography
Covering its History and Use in Education and Research
Prepared by
John D. Sterman
Sloan School of Management
Massachusetts Institute of Technology
Cambridge, MA 02139
(617) 253-1951 (voice); (617) 253-6466 (fax); jsterman@mit.edu (email)
April 1992; revised July 1992
The Beer Distribution Game dates to the earliest days of system dynamics. The game has been used for three decades as
an introduction to systems thinking, dynamics, computer simulation, and management. It has been played by thousands of
people, all over the world, from high-school students to CEOs of major corporations. The references below provide useful
information for those who want to follow up the experience of the game. These works describe the history of the game,
the equations for simulating the game on a computer, the success of organizational change efforts based on the original
model embodied in the game, the psychological processes people use when playing, and even how these processes can
produce chaos.*
Forrester, J.W. (1958) Industrial Dynamics: A Major Breakthrough for Decision Makers. Harvard Business Review,
36(4), July/August, 37-66.
The first article in the field of system dynamics. Presents the production-distribution system as an example of dynamic
analysis of a business problem. Reprinted in Roberts (1978).
Forrester, J.W. (1961) Industrial Dynamics. Cambridge MA: Productivity Press.
Contains the material in Forrester 1958 expanded to include additional discussion of policies to improve performance
in the production-distriubtion system. Also includes complete equations for a computer model of the system from
which the Beer Game was derived. Describes the results of many policy experiments. Industrial Dynamics is the
classic work in the field and remains an extremely useful reference and text thirty years after publication.
Jarmain, W. E. (ed.) 1963. Problems in Industrial Dynamics. Cambridge, MA: MIT Press.
Contains a description of an early version of the Beer Distribution Game
MacNeil-Lehrer Report, (1989) Risky Business - Business Cycles, Video, Public Broadcasting System, aired 23 October
1989.
Videotape showing students in John Sterman's Systems Dynamics course at MIT playing and discussing the Beer
Game. Relates the game to boom and bust cycles in the real world. Excellent in debriefing the game, and helpful to
those seeking to learn how to run the game. Copies available from System Dynamics Group, E60-388, MIT,
Cambridge MA 02139.
Mosekilde, E., E. R. Larsen & J. D. Sterman (1991). Coping with complexity: Deterministic Chaos in human decision
making behavior. In J.L. Casti & A. Karlqvist (Eds.), Beyond Belief: Randomness, Prediction, and Explanation in
Science, 199-229. Boston: CRC Press
Shows how simple and reasonable decision rules for playing the Beer Game may produce strange nonlinear
phenomena, including deterministic chaos.
Radzicki, M. (1991). Computer-based beer game boards. Worcester Polytechnic Institute, Dept. of Soc Sci and Policy
Studies, Worcester, MA 01609-2280
Beer game boards in PICT format for Macintosh computers available on disk for $5.00; all proceeds go to the System
Dynamics Society.
Thomsen, J.S., E. Mosekilde, & J.D. Sterman (1992). Hyperchaotic Phenomena in Dynamic Decision Making. Systems
Analysis and Modelling Simulation, forthcoming.
Extends earlier papers by Moskilde, Sterman, et al. to examine hyperchaotic modes in which the behavior of the beer
distribution system may switch chaotically among several different chaotic attractors (for aficionados, "hyperchaos"
exists when a dynamical system contains multiple positive Lyapunov exponents).
Roberts, E.B., ed. (1978) Managerial Applications of System Dynamics. Cambridge, MA: Productivity Press.
Excellent anthology of early applied system dynamics work in organizations, including analysis of efforts to
implement the results of the model which led to the Beer Game.
Roberts, E.B. (1978) Equations for the Production-Distribution System, in Roberts, E.B.(ed.) Managerial Applications of
System Dynamics. Cambridge, MA: Productivity Press.
Presents documented equation listing for the production-distribution system based on Forrester (1961), in the
DYNAMO computer simulation language.
Senge, P. (1990) The Fifth Discipline. New York: Doubleday.
Excellent non-technical discussion of the Beer Game, and systems thinking principles generally.
Sterman, J.D. (1984). Instructions for Running the Beer Distribution Game. D-3679, System Dynamics Group, MIT, E60-
388, Cambridge, MA 02139.
Explains how to run and debrief the Beer Game, including layout of boards, set up, play, and discussion. Incorporates
debriefing notes by Peter Senge. Some people have found this document, in conjunction with the MacNeil/Lehrer
video and plenty of practice, is sufficient to enable them to lead the game successfully.
Sterman, J.D. (1988) Deterministic Chaos in Models of Human Behavior: Methodological Issues and Experimental
Results. System Dynamics Review, 4, 148-178.
The decision rules people use when playing the Beer game can lead to deterministic chaos.
Sterman, J.D. (1989). Modeling Managerial Behavior: Misperceptions of Feedback in a Dynamic Decision Making
Experiment. Management Science, 35(3), 321-339.
Detailed analysis of Beer Game results. Examines why people do so poorly in the Beer Game. Proposes and tests a
model of the decision making processes people use when playing the game and shows why they do so badly.
Additional information on systems dynamics, including publications, simulation games, management flight simulators,
journals, etc. is available from John Sterman at the address above.
*If you know of additional publications which discuss aspects of the game not included in this bibliography
please send a copy to John Sterman at the address above so they can be incorporated in future r
