NGS Field Strength Changes Between Sessions

UsuallyDummy

I recently played in the Yorkshire Waddington Cup Final, with seven teams in total. I was susprised to see the NGS field strength change between sessions even though nothing else changed.

First session was played as multiple teams, four board rounds against the other six teams, then about an hour's break for tea. The second session repeated the exact same movement with the exact same people in exactly the same seats.

When the results appeared on Pianola, the strength of the field reduced slightly by 0.19% between the two seesions:

1st session: https://app.pianola.net/Results/Session467728 - Field Strength = 58.03%
2nd session: https://app.pianola.net/Results/Session467729 - Field Strength = 57.84%

How did everybody drop by 0.19%? With 24 players I think this is the equivalant of one player losing 4.5% between sessions, or nine players dropping 0.5%.

I thought NGS was (almost*) a zero-sum game in each session - we are effectively trading NGS points with each other.

(Almost*) = There will be tiny variances depending on the value of the oldest scores dropping off the scale, but that should be negligible in this case.

Senior_Kibitzer

"Almost" would be right if all the players had had mature grades. I know of one of the players who had played only a tiny number of boards previously, and he had a disastrous first session in the event and the effect thereof would easily account for the difference between sessions that you quoted.

There may have been similar cases beyond that of the person of whom I know. The Full Guide FR 11 would be relevant as well as the sections on grade initialization.