Computer Dice

Forum Archive : Computer Dice

Error rates with computer dice

From:   NoChinDeluxe
Address:   (none)
Date:   17 February 2011
Subject:   My little dice experiment
Forum:   2+2 Backgammon Forum

I use gnubg, and there have been some moments where I wanted to pull my
hair out at some of the ridiculous rolls that occur in my games against it.
The main scenario that seems to come up a lot is that when the game comes
down to a straight race at the bearoff, one player will throw multiple
doubles to win the match.

I suspect that this is a case of selective memory, where these games have
had the biggest impact on me emotionally, and so I tend to remember them
more. But I also know that in my live games, it seems that the winner is,
more often than not, the player who out-played his opponent, and not the
player who got the ultra joker to win the match. So I started playing gnu
with manual dice just for fun to see what would happen. It turned out that
I was achieving much better error rates and winning more games. So I
decided that I should start documenting my experience with this so I can
keep some long-term results.

So to start this experiment, I decided to play 10 games in a row against
gnu. I would play 3 with manual dice, 3 with auto dice, then alternate the
last four games. The results blew my mind! Here are the results for the
first 10 matches, with the dice type used, the winner of the match, and my
snowie error rate:

             Dice     Winner   Error Rate
    Game 1:  manual    gnu        4.9
    Game 2:  manual    gnu        5.0
    Game 3:  manual    me         6.1
    Game 4:  auto      gnu       46.7
    Game 5:  auto      gnu       38.7
    Game 6:  auto      gnu       19.0
    Game 7:  manual    gnu        6.0
    Game 8:  auto      gnu       36.8
    Game 9:  manual    me        14.8
    Game 10: auto      gnu       31.0

I'm stunned, and I honestly can't explain it. My first thought was that
maybe when I use gnu's dice I play more quickly than usual and make dumb
mistakes, whereas taking the time to roll the manual dice each time slows
down my game and causes me to analyze a bit more before I make my decision.

I will also say that I noticed more doubles being thrown in the auto dice
games, although there was one manual dice game that had quite a few doubles
as well. Is there anything documented that shows that dice algorithms tend
to come up with more doubles than they should?

I still don't think the bots cheat or the dice are fixed or any of that
foolishness, but it's clear that I play better when manually rolling. Any
thoughts? Is this all just psychological? Did I get those awful error rates
on the auto dice games because I EXPECTED to play poorly with the auto

Aaron W.  writes:

This seems reasonable to me. I know I get clicky sometimes when playing and
make mistakes that I wouldn't have made if I had took a second to look at
the position. I also know I miss cubes when I'm clicking quickly.

Although a pattern is clearly emerging, it would be interesting to see
whether it continues over the next 10 games or so. 10 games of backgammon
is a very small sample, and it's not completely implausible that this might
just be a weird string of coincidences.

Bill Robertie  writes:

You've found the answer already: playing slowly and carefully (which the
manual dice forced you to do) has a HUGE effect on your error rate.

I performed a similar experiment on myself some years ago. I played a set
of matches against Snowie where I only played when I was alert, well-
rested, and eager to play. I'd play only one match at a time, after which I
would do something else.

I then played a series of matches under non-optimal conditions: I was
tired, I didn't feel like playing, I had a cold, or I forced myself to play
at blitz speed. My error rate in the second group was more than twice that
of the first group. Now, when I go to a tournament, I'm even more careful
to make sure I arrive at least a day early, get a good night's sleep every
night, eat on a regular schedule, and focus carefully on each match. It
makes a big difference.
Did you find the information in this article useful?          

Do you have any comments you'd like to add?     


Computer Dice

Dice on backgammon servers  (Hank Youngerman, July 2001) 
Does Agushak Backgammon cheat?  (Mr Nabutovsky, June 2000) 
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) 

[GammOnLine forum]  From GammOnLine       [Long message]  Long message       [Recommended reading]  Recommended reading       [Recent addition]  Recent addition

  Book Suggestions
Computer Dice
Cube Handling
Cube Handling in Races
Extreme Gammon
Fun and frustration
GNU Backgammon
Luck versus Skill
Magazines & E-zines
Match Archives
Match Equities
Match Play
Match Play at 2-away/2-away
Opening Rolls
Pip Counting
Play Sites
Probability and Statistics
Source Code
Strategy--Bearing Off
Strategy--Checker play


Return to:  Backgammon Galore : Forum Archive Main Page