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Polis: Fight for the Hegemony» Forums » General

Subject: Is the included D4 die sufficiently random? rss

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Tom
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Great game, love the components.

I was disappointed to see a D4 die in the box. I find rolling the four sided dice unsatisfactory since it just hits the table with no bounce or roll. Also, this tiny thing looked cheap leading me to have no confidence that the die rolls will be completely random.

I was tempted to buy a decent sized D8 and use that, but first my curiosity got me to pour a glass of wine, sit out on the porch and do an experiment.


Purpose:

Determine if the D4 provided in Polis: Fight for Hegemony is suitable for game use.

Methodology:

Roll the die 250 times using a dice cup and dice box, recording the results. Calculate the percentage each number came up. Examine the results to determine if there is an even distribution.

note: make sure it rolls around sufficiently in the cup before throwing the die.

Equipment:

A dice cup, a game of Shut the Box to use as a dice tray, pencil. paper. wineglass. wine. calculator.



Observations and Calculations:

1 rolled 72/250 (28.8%)
2 rolled 61/250 (24.4%)
3 rolled 68/250 (27.2%)
4 rolled 49/250 (19.6%)

Recommendations:

1)My Statistics and Probability textbooks are long ago thrown out. If anyone wishes to comment below regarding sample size of 250 is adequate or if the results fall within standard deviation, please do.

2)The die did not often roll once leaving the dice cup. A truly random roll requires using the cup to bounce the die around.

Conclusions:

1)I suspect the die is quite random if you throw it right (a bit like dice at the craps table it HAS to bounce in the cup.) The fact that it does not easily roll suggests to me that the bias other dice have because they CAN roll more easily (such as a cheap D6) is not present in even a cheap D4

2) I do not feel I have demonstrated that this D4 is completely random.

3) Close enough for game purposes.

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David desJardins
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Re: Is the included D4 die completely random?
TomAquin wrote:
Observations and Calculations:

1 rolled 72/250 (28.8%)
2 rolled 61/250 (24.4%)
3 rolled 68/250 (27.2%)
4 rolled 49/250 (19.6%)


The chi-square statistic is 4.88 with 3 degrees of freedom. This is not high enough to be considered a statistically significant deviation from uniform. You would need more data to confirm the die is biased, if it is.

Since the orientation of the die when coming out of the cup is basically random, it doesn't matter whether it rolls or not. If it had a bias (e.g., the center of gravity is closer to one side) that bias would affect a d4 just the same as a d6 or d20. In fact, it might affect the d6 or d20 more than the d4.
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S. R.
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Re: Is the included D4 die completely random?
If the rolling is of any issue, you could always use a D8 or a D12, available in any well-sorted game store (I reckon). I know exactly what you mean, but I actually like the D4 due to its weird shape, and I usually throw it hard on the table (without dice cup) so that it bounces. That makes it hard to control where it lands, though...
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Tom
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Re: Is the included D4 die completely random?
DaviddesJ wrote:
The chi-square statistic is 4.88 with 3 degrees of freedom. This is not high enough to be considered a statistically significant deviation from uniform. You would need more data to confirm the die is biased, if it is.


Thanks for this analysis, David.

ps - I could get more data, but I ran out of wine. Good 'research' is so expensive.
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Andrew MacLeod
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And when, exactly, are we playing Churchill again?
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Re: Is the included D4 die completely random?
Greetings, Tom! As a fellow Londoner (and recent convert to the cult of Polis), please feel free to drop me a geekmail if you want to have a game of Polis...with whatever die you choose!

Also, I sneaked a peek at your profile, and I see you're looking for a local game group. I belong to one....which usually only has two people during the summer months! We'd love to have you join us. Send a geekmail about that, too, if you'd like.
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Tom
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Re: Is the included D4 die completely random?
Thanks for your comments, Dumon. I agree.

Dumon wrote:
If the rolling is of any issue, you could always use a D8 or a D12, available in any well-sorted game store (I reckon). I know exactly what you mean, but I actually like the D4 due to its weird shape, and I usually throw it hard on the table (without dice cup) so that it bounces. That makes it hard to control where it lands, though...


Throwing hard, convincing your opponent to also do so, arguing whether rolls that land under the table or bounce off walls are valid, explaining to your wife how her heirloom vase got broken, yelling at the dog not to eat the die that just landed in his food dish.....I may take your advice and get a D12.
 
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S. R.
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Re: Is the included D4 die completely random?
On the other hand, you would miss out on a whole lotta adventure and fun, it seems!
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A Day
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Re: Is the included D4 die completely random?
I recommend the "Triple 4"

http://www.doublesixdice.com/collections/triplefours

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Tom
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Re: Is the included D4 die completely random?
b a n j o wrote:
I recommend 2d10, if you don't like the 1d4.


Thanks for the suggestion. Please expand on how to use these for this game?
 
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Tom
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Re: Is the included D4 die completely random?
AGRAYDAY wrote:


Those would work nicely. Is anyone aware of anything like that available in FLGS's?
 
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Serious? Lee
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AGRAYDAY wrote:

I've added one of these to my copy of Polis. I really like the way it rolls.
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Gregorio Morales
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TomAquin wrote:
b a n j o wrote:
I recommend 2d10, if you don't like the 1d4.


Thanks for the suggestion. Please expand on how to use these for this game?


1 out of 4 it's the same as 25 out of 100
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Tom Swider
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You can buy precision dice to get higher quality dice in terms of production tolerances.
 
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