Bottleneck or Mirage?

1 Look at the production line below. Which station is the bottleneck?

2 Click a station, choose an improvement, and hit Apply

3 Check the Mirage Index — did system throughput actually increase?

⚙ Production Line

Station to improve

Improvement type

Percent reduction20%

Number of stations (3-8)5

📊 Results

Baseline TP

New TP
-

System Gain

Local Gain

Mirage Index
-

New Bottleneck

💼 Interview Tip

Goldratt Rule #5: "An hour saved at a nonbottleneck is a mirage." System throughput equals the capacity of the bottleneck (minimum capacity station). Improving any other station adds zero throughput \u2014 it only adds idle time. In interviews, mention the 5-step TOC process: Identify \u2192 Exploit \u2192 Subordinate \u2192 Elevate \u2192 Repeat.

Instructor Notes

Have teams guess the bottleneck before clicking. Then improve a NON-bottleneck by 30% and check the Mirage Index (should be 0%).
Then improve the actual bottleneck by just 10%. The Mirage Index jumps to 100%. Small improvement at the right place beats a big one at the wrong place.
After improving the bottleneck, a new one appears. This demonstrates the TOC cycle: go back to Step 1.
Click Shuffle to create fresh instances and repeat the exercise.

Mirage!