## Arrow switching in a contest with 2 strong pairs

Consider a contest between 14 pairs, 12 of whom are equally strong,
while the other 2 pairs always score a top. If they play a board in the
same direction this will be a shared top of course, and if they play
against eacht other they get the same result as the other pairs.
First the tournament director uses a complete Mitchell-14 movement.
Thus each pair plays in a fixed direction throughout and the 7 NS pairs
play against all 7 EW pairs. How the scores will be distributed depends
of course on whether the 2 top pairs had different wind directions or
not. For each of the possible choices of the pair numbers of the 2 top
pairs we have calculated the corresponding 14 scores. The following
graph shows the distribution of the scores taking all these possibilities
into account.
The 2 possible top scores are close together, but the other pairs have
scores that vary from 33 to 50%. The most frequent value is 42.86%.
Now the same contest, but with a movement that contains one arrow switch
The scores of the 12 equally strong pairs now are a lot closer together.
The extremes are now 40.48 en 46.43%
Finally the devastating result of a movement with 2 arrow switches: