[Fluffy]

I have got to know about the offensive/defensive ratio concept from many years on the forums, but I wonder where the term comes from, wouldn't surprise me it started on the "fought the law" book from Lawrence.

[JLOGIC]

You think the term offense to defense ratio was invented a few years ago (or whenever fought the law was written)? Interesting.

[Fluffy]

completelly uknown in spannish, not even a bad translation

[gnasher]

It was discussed at length by Robson and Segal in 1993, 11 years before I Fought the Law was published.

I was vaguely aware of the phrase some time before that, but possibly only because I played at the same club as Segal and Robson.

[JLOGIC]

Fluffy, on 2011-June-02, 14:33, said:

completelly uknown in spannish, not even a bad translation

No one has ever compared how good the offensive value of their hand is compared to the defensive value in a spanish speaking country? Am I wrong that ODR is not a formalized concept, that is simply all that it means? In that case, I cannot believe that you thought that it was "invented" by fought the law, maybe they formalized it in some way that I am unaware of, otherwise...lol.

[babalu1997]

JLOGIC, on 2011-June-02, 14:44, said:

No one has ever compared how good the offensive value of their hand is compared to the defensive value in a spanish speaking country? Am I wrong that ODR is not a formalized concept, that is simply all that it means? In that case, I cannot believe that you thought that it was "invented" by fought the law, maybe they formalized it in some way that I am unaware of, otherwise...lol.

perhaps not with that exact terminology, but edgar kaplan in the early 60s taught about the difference between quick tricks and defensive tricks, and even offered translation ruloes.

the more distributional the hand, the more offensive it is

plus all the discussion about neutral hands for offense/defense

if memory does not fail me some books by ron klinger discuss this issue too.

[mgoetze]

babalu1997, on 2011-June-02, 14:59, said:

perhaps not with that exact terminology, but edgar kaplan in the early 60s taught about the difference between quick tricks and defensive tricks, and even offered translation ruloes.

That is not quite what Robson and Segal talked about when they introduced ODR. Aces are "ODR-neutral" for them, and as for Kings, Queens, and Jacks, it depends whether they are in "our" suits or "their" suits.

Read up on it in their book, available from http://bridge.mgoetz...t/bbf.html#comp .

[babalu1997]

mgoetze, on 2011-June-03, 00:54, said:

That is not quite what Robson and Segal talked about when they introduced ODR. Aces are "ODR-neutral" for them, and as for Kings, Queens, and Jacks, it depends whether they are in "our" suits or "their" suits.

Read up on it in their book, available from http://bridge.mgoetz...t/bbf.html#comp .

Thanks, I do have that book. For Kaplan queens and jacks in the opps bid suit are assigned increased defense values dpending on their poaition.

But many authors before Robson and segal, have the tackled the topic of shifting hand valuation, with different terminology, you can even get references to it from Mollo's Declarer Play Technique. And, of course, from Lawrence's Complete book of hand valuation.

[helene_t]

R/S offered some argument why it should be O/R rather than O-D. I never understood this. To me, the difference (rather than the ratio) between the number of tricks I can take in offense and the number of tricks I can take in defense are what matters. Say that my O-D is 4 and p's is 2, then our combined O-D is six tricks and is lawful to bid 4♠ over 4♥ since if we make four tricks in defense we also make ten tricks in offense.

You can't use O/D in the same way. Oh well if the scale is exp(#tricks) rather than #tricks then I am cool with ratios but that probably isn't the idea.

[gwnn]

I don't think they were very specific if it was O/D or O-D. They just said that your overall hand strength is not as important as the ratio. They don't speak about exact mathematical formulas or even mention any numbers at all.

[kenrexford]

Sometimes I think OCD has more impact on bidding than is given credit or recognized.

[whereagles]

Yes, R/S weren't too specific as whether it was O/D or O-D. The latter case is much more user-friendly and you can even cook up some rules for preempting from it, e.g.:

O-D = 5 --> you're ok for a 2-level preempt at R/R or G/G (4 for G/R, 6 for R/G)
O-D = 6 --> you're ok for a 3-level preempt at ...
etc...

[glen]

Predating Segal & Robson, there was the concept of "Offensive Premium", which "determined how worthless the hand is on the defensive relative to its playing value".

In reference to Ken's post, OCD predates bidding, but bidding added the necessary structure.

[Zelandakh]

In answer to the OP question I believe ODR comes from Andrew Robson - this one of his key skills as a bridge author and part of his success formula. As others have suggested differentiating between offensivee and defensive values has come up in various guises down the years. The oldest I can think of is from Culbertson, where his evaluation method (HTs) is essentially a rough guide to the defensive value of the hand but then when considering some bids he prefers to use playing tricks which is a rough guide to the offensive power of a hand. Naturally this is a long way from ODR though!

I think it is pretty irrelevant whether you count tricks, ratio features, or even use 2 different evaluation methods for offense against defence - what matters is that the evaluation provides a good basis for decision-making for both members of the partnership.