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How fair are Howell movements? (Matchpoints)

I have been a club director for a number of years, and one of the things that I have always "known" is that a Howell movement in which all pairs meet all other pairs, and all pairs play all the boards is the epitome of fairness when it comes to movements. But this afternoon, it occurred to me that this might not be the case.

The problem is that vulnerability conditions vary from one pair to the next. Take the 7 table Howell movement as an example, as configured by ACBLscore. It turns out that pair 3 in this movement has 9 instances of favorable vulnerability, but only 4 instances of unfavorable vulnerability. (In the other 13 instances, vulnerability is equal.) On the other hand, pair 7 has just the reverse: nine cases of unfavorable vulnerabilityVs only four cases of favorable vulnerability. Six pairs are split 8-5 (three each way), while the remaining six pairs are split 7-6.

It seems to me that favorable vulnerability is a distinct advantage. How much of an advantage is open to question, and that's my first question to the group. My gut feeling is that favorable vulnerability is worth about a queen or so, but maybe I'm overestimating it.

I have only looked at the 7 table Howell, but I suspect that all Howell movements suffer from this defect, and perhaps scrambled Mitchell movements as well. As near as I can tell, this aspect of fairness has been pretty much ignored. Am I making a mountain out of a molehill?

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