d12 or 2d6?

Chawanat Nakasan#5210501663

Seminar Presentation

d-What?!

• Dice.• In Thailand, we use 3d6.• Familiar?

http://77.nationchannel.com/video/92524/

d12?

• This, is a twelve-sided die, or “d12.”• We use it for more complex games like

hardcore RPGs.

(Public Domain clipart)http://commons.wikimedia.org/wiki/File:Dice7.png

Property of dice

• Lots, but most important is: It should be fair.

1 2 3 4 5 6 7 8 9 10 11 120.000.010.020.030.040.050.060.070.080.09

PMF of d12

Prob.

But I don’t have a d12!

• Can I use two “d6” instead?• NO. d12 != 2d6.

Why d12 != 2d6

• “Minimum Roll” of d12 is 1.• But the min-roll of 2d6 is 2!

http://commons.wikimedia.org/wiki/File:2-Dice-Icon.svg

!=

Furthermore…

• We have taken Probability course. We know…– That d12 has prob. of 1/12 per side. Equally.– But for 2d6 it’s another matter.

http://commons.wikimedia.org/wiki/File:2-Dice-Icon.svg

!=

Outcomes of 2d6Result 1 2 3 4 5 6

1 2 3 4 5 6 7

2 3 4 5 6 7 8

3 4 5 6 7 8 9

4 5 6 7 8 9 10

5 6 7 8 9 10 11

6 7 8 9 10 11 12

Count them.Roll Value Count

2 1

3 2

4 3

5 4

6 5

7 6

8 5

9 4

10 3

11 2

12 1

Sum 36Public Domain chart: http://commons.wikimedia.org/wiki/File:Dice_Distribution_(bar).svg

Comparison

Comparison

Comparison

But I don’t have d12!

• Use anything, as long as it’s “fair”• Even this, if it’s fair, is OK:

http://news.hatyaiok.com/wp-content/uploads/2012/10/12-53.jpg

Summary

• d12 != 2d6• Minimum roll value not equal• d12: all roll values are equally likely• 2d6: roll values’ probabilities are weighted

towards center• Effect is intensified in 3d4, 4d3, …• This means: Use proper dice when playing!

The end.