# Can one show that a majority of bridge hands could have been successfully defended?

In noting the importance of defense in overall bridge scores, a bridge teacher opined that half or more contracts were either defeated or could have been.

I was wondering if available records of the results in pairs or duplicate tournaments could prove or disprove this statement. Specifically, I was wondering about the proportion of "contested contracts" that some declarers made, and some defenders defeated.

For our purposes, a "contested contract" in a pairs tournament will be one where the declarer made it in one room, and the defense defeated in the other room. A declarer's contract will be one that both declarers made, and a defender's contract will be one that both defenders defeated.

A "contested contract" in a duplicate tournament will be one that declarers and defenders made and defeated in non- lopsided proportions. A declarer's contract will be one that most declarers made, and a defender's contract will be one that most defenders defeated.

Are there percentage breakdowns of contested, versus declarers' and defenders' contracts from tournaments? And do they show that the percentages of defeated plus contested (and presumably defeatable) contracts is greater than 50 per cent? Or are declarers supposed to make more than 50 per cent of their contracts because bidding systems are constructed that way?

• A tough theoretical question- if you wish this is useful source- Vugraph project from which you might do your own analysis sarantakos.com/bridge/vugraph.html – user2617804 Nov 12 '13 at 4:12
• 'The number of contracts that were or could have been defeated' is about as useful a statistic as 'the number of days when it rained or might have done'. – Tim Lymington Nov 12 '13 at 23:35