Supply Chain LabBullwhip ArenaLab Home
Live class game · 4–35 students

Bullwhip Arena

Five roles, two identical demand shocks, one visible lesson. Round 1 is Chaos: local information and no talking. Round 2 is Collaboration: teams share the chain view, coordinate, and try to tame the bullwhip. Pick one of four demand scenarios, and every chain in the room plays the same one.

How to run this in class - teaching guide →

SSupplier
MManufacturer
DDistributor
WWholesaler
RRetailer

Goods flow right. Orders flow left. Both are delayed - which is why a small change at the customer can become a huge upstream wave.

Build the room

Enter the actual attendance. The model balances the competition and gives you the physical seating map.

A single permanent step in demand is enough to whip the chain.

Fairness rule: every student has one decision seat. Empty roles use the same calm Bot policy; an automated Benchmark chain gives small classes a rival.

Lost the tab or swapped laptops? Type the join code showing on the projector to take the room back over.

About this tool

Bullwhip Arena - the five-tier Beer Game

The concept

A step from 4 to 8 customer units travels through five delayed decisions. When every role reacts only to its own local signal, upstream order variance becomes far larger than demand variance - the bullwhip effect.

How it works

Round 1 (Chaos) hides the chain and bans conversation. Round 2 (Collaboration) reveals teammates’ inventory, backlog and orders. Both rounds replay the identical 12-week demand trace, so any improvement is real rather than luck. The instructor picks which trace the class feels - a classic step change, a promotion spike and its hangover, a steady growth ramp, or noisy demand with a flat average - so the same cohort can play more than once and the week the shock lands is not common knowledge.

Winning strategy

Order close to what you actually see, count the stock already moving in the pipeline before reordering, and tell the tier upstream what is coming. Weekly cost is inventory × $1 plus backlog × $2 across all five roles. Champion = lowest total cost among teams with at least 80% customer service - and if no chain clears 80%, no champion is awarded, because a cheap chain that leaves customers unserved has not solved the problem. The automated Benchmark simply orders what it sees; with hindsight a coordinated chain can finish roughly 20% below it, which is the whole prize.

Projector view