Simulation № 2
Polya Urn Model
Imagine an urn with five different colors of marbles. At each step, one marble is drawn at random and returned to the urn with an extra marble of the same color. The distribution is recorded and the process repeats 100 times.
The model demonstrates the self-reinforcing properties of success. Run it a few times and you may occasionally be surprised by the results. For more, see the Wikipedia article on the model.
How many marbles start in the urn?
Early draws are mostly luck — but each lucky draw improves that color's odds on the next one. By draw 100 the "richest" color usually got rich early, not because it was better.
Share of the urn, draw by draw100 draws
| Marble | Start | Final | Share of urn |
|---|