The offence to defence ratio (ODR) refers to how a hand will perform differently when it is played as a declarer or a defender. A high ODR means that the hand is better played as a declarer, while a low ODR means that the hand is better played as a defender. It is not a formalised concept and has no clear mathematical formula for it.
For example, the following hand has a very high ODR:
It can be played greatly in ♥s, guarantees 7 tricks even opposite a partner with no values, but can take at most 2 tricks if the contract is in a suit other than ♥s.
In contrast, the following hand has a very low ODR:
No matter what suit it is played in, the short suits generally perform well because they have high honours in them.
Normally, the following are good for an offensive hand:
- long and solid trumps
- side shortness
and the following are good for a defensive hand:
- side honours
- balanced shape