Computer Dice

Forum Archive : Computer Dice

GamesGrid: Too many jokers?

From:   Gregg Cattanach
Date:   7 September 2001
Subject:   Too many Jokers on-line?

One common complaint I hear from some players about on-line dice is
'there are too many jokers'.  This comment seems especially prevalent
related to GamesGrid (but probably only because I have lots of friends
that play there), but I gather a variety of players at any BG server
often make this complaint. I hear this even from some very top-notch
players.  I've always been skeptical of the notion that the dice are
somehow skewed, either intentionally or through some defect in the
random number generator.  Granted pseudo-number generators do NOT
produce a truly random sequence of numbers, but as long as there is no
way to identify the difference between a pseudo-random sequence and an
actual random sequence of rolls, then the pseudo-random sequence is
adequate for the task.

I decided to collect some data (what a concept!) to test the 'too many
jokers' theory. I found 20 long matches (several over 25 games per
match) played over the board with real dice (various web sources), and
compared them to an equivalent number of matches (similar number of
total dice rolls) on matches I'd saved from GamesGrid. The matches
were selected at random before looking at the results. Using Snowie, I
then did a simple joker count for each player and added them up. I
used a threshold of 0.350 for the jokers which is lower than the
suggested Snowie default value.  This seemed to work well, because it
captured more 'joker' rolls without trivializing the concept.  A swing
of 0.350 or more on a single roll is usually perceived as quite a good
(or bad) roll by most players.  Also, the joker calculation is not
impacted by the skill of the players. A roll is counted as a joker if
the equity swing is 0.350 or more when played in the best way
according to Snowie.

Here are the results:

             #rolls   Jokers PL1   Jokers PL2   Joker every X rolls
REAL DICE:    10325       486         497            10.50
GAMESGRID:    11394       491         500            11.50

In this sample, the joker frequency is actually LOWER at GamesGrid
than compared to these real dice matches.

There isn't any bias toward the winner or the loser of each game as
both sides are being counted.  Also, Snowie adds to the joker count
the 'anti-jokers' which are rolls that are bad for the roller.  These
are counted as jokers for the non-roller.  This isn't a gigantic
sample, but I think if there was some real bias for GamesGrid to be
giving someone 'exactly what they need' too often, it would appear in
these numbers.

So why do lots of people think this about the Grid (and servers in
general)?  I think one possibility is that it is easy to trust dice
you throw yourself, but playing on-line is like playing a match where
a third person is throwing dice in a box and announcing what your roll
is, without you seeing the numbers. Also, the speed of play on-line
can give the emotional experience of a lot of good and bad rolls
coming quickly, when the frequency of these exceptional rolls is
nearly identical to what you get over a real board.  The
over-the-board game generally is slower, if only because of the time
taken to shake, roll, and move the checkers.

I thought this was interesting and wanted to share with the group :)

Gregg Cattanach
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Computer Dice

Dice on backgammon servers  (Hank Youngerman, July 2001) 
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Does BG by George cheat?  (George Sutty, Nov 1995) 
Does Backgammon NJ cheat?  (Greg+, June 2010) 
Does Cybergammon cheat?  (Goto Informatique, Aug 1996) 
Does David's Backgammon cheat?  (Joseph B. Calderone, June 1998) 
Does GNU Backgammon cheat?  (Robert-Jan Veldhuizen, Nov 2002) 
Does Gammontool cheat?  (Jim Hurley, Sept 1991) 
Does Hyper-Gammon cheat?  (ZZyzx, June 1996) 
Does Jellyfish cheat?  (Fredrik Dahl, June 1997) 
Does MVP Backgammon cheat?  (Mark Betz, Oct 1996) 
Does MonteCarlo cheat?  (Matt Reklaitis, June 1998) 
Does Motif cheat?  (Rick Kiesau+, Mar 2004)  [Long message]
Does Motif cheat?  (Billie Patterson, Feb 2003) 
Does Motif cheat?  (Robert D. Johnson, Oct 1996) 
Does Snowie cheat?  (André Nicoulin, Sept 1998) 
Does TD-Gammon cheat?  (Gerry Tesauro, Feb 1997) 
Error rates with computer dice  (NoChinDeluxe+, Feb 2011) 
FIBS: Analysis of 10 million rolls  (Stephen Turner, Apr 1997)  [Recommended reading]
FIBS: Are the dice biased?  (Kit Woolsey, Oct 1996) 
FIBS: Entering from the bar  (Tom Keith+, Apr 1997) 
GamesGrid: Too many jokers?  (Gregg Cattanach, Sept 2001) 
GridGammon: Are the dice random?  (leobueno+, Sept 2011) 
Jellyfish: How to check the dice  (John Goodwin, May 1998)  [Recommended reading]
Jellyfish: Proof it doesn't cheat  (Gary Wong, July 1998) 
MSN Zone: Security flaw  (happyjuggler0, June 2004) 
Official complaint form  (Gary Wong, June 1998)  [Recommended reading]
Randomness testing  (Brett Meyer+, Dec 2010) 
Safe Harbor Games dice  (Michael Petch+, Aug 2011) 
Synopsis of "cheating" postings  (Ray Karmo, Feb 2002) 
Testing for bias  (Kit Woolsey, Jan 1995) 
The dice sure seem unfair!  (Michael Sullivan, Apr 2004) 
Too many repeated rolls?  (Stephen Turner, Mar 1994) 
Winning and losing streaks  (Daniel Murphy, Mar 1998) 

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