Computer Deals (Computer Hands) - Since the mid 1990's, the ACBL has
prohibited tourney Directors from "tweaking" hands. Here is an
overview of the ACBL process to generate and distribute tournament hands.
Rumors circulate about how computer dealt hands are more distributional than
seen at a Club game. First, neither the ACBL Director In Charge, nor
anyone else involved with making boards are allowed to pick and choose hands
based on certain characteristics. The master ACBL computer which "deals"
hands for all tourneys in North America is based on random numbers to ensure
the hands are truly random. So the ACBL files sent to the Director
receives hands that closely represent hand patterns you would find in bridge
tables. This may seem surprising since some Club players seem to encounter
flatter hands, as opposed to wilder distribution with computer-generated
hands. Why is this true?
It turns out humans often do not tend to shuffle hands
enough to ensure random distributional patterns. As you may have heard,
mathematicians (Aldous and Diaconis) have demonstrated that the dealer
should make seven good interleaved riffle shuffles (also called the faro
shuffle) to ensure the pack is randomized between deals. Actually, four good faro
shuffles do a fairly good job to randomize the pack. But in reality, bridge
dealers often make fewer shuffles. Some human dealers make few interleaves,
less riffles, or worse yet, use sub-standard methods such as an over handed
shuffle which does practically nothing to shuffle the deck. You get the
picture - poor shuffles generates in flatter hands.
Here's the ACBL approved process for tournaments within its jurisdiction:
1. ACBL programmer Jim Lopushinsky wrote a program that ensures each hand is
truly random. Rather than using a simple internal pseudo random number, Jim
requires the ACBL hand administrator (Martha Walls) to shuffle a pack of
cards at least 7 times and manually enter the first hand into the computer.
Thereafter, the computer uses this data to "seed" subsequent hands along
with the computer's internal clock to ensure randomness. Jim ran numerous
simulations to ensure the hands generated matched statistical averages in
2. The ACBL hand administrator, who generated over 10,000 sessions of 36
hands each year, prints out hand records in two formats: one to make boards,
one for player hand records. These sheets are sealed and sent to the
Thus, the Director does not have the opportunity to "pick and choose" one
hand or exclude another hand - if the Director skips certain boards, get
suspicious! Some years ago Directors actually did tweak the hands,
believing it would enhance the game. Of course, doing so would lead to
skewed results and cause the players to make guesses based on the
characteristics of each Director.
Also see the
for further details