It is tough to describe your hand and evaluate your partner's hand after several
levels of bidding space
has been taken out by an opponent's preemptive bidding.
The points required to bid at the different levels are shown below:
Level
1
2
3
4
Direct seat, non-vul
11
13
15
17
Direct seat, vulnerable - add 2
13
15
17
19
Balancing seat, non-vul - subtract 4
7
9
11
13
Balancing seat, vulnerable - subtract 4 and add
2
9
11
13
15
The points include "length" points i.e. add 1 point for every card after the fourth in a suit.
This applies for any bid - double, suit bid or no-trump bid; for no-trump opponent's suit should be
stopped.
Response
Over a 2-level preempt there are conventions like
lebensohl
to help differentiate between different kinds of hands.
Conventions like Western cue-bid help identify controls in the preempted suit.
In some cases it will take a guess to determine the right level and the strain to play in.
3-level preempts are much harder to handle and there will be quite a few cases of guesses.
If responder is a passed hand, it is better to bid the hand to the hilt.
For example the bidding has gone P - 3D - Dbl - P back to the dealer and dealer holds 7 4 2
K Q 9 8 4
5 4
Q J 9
Dealer should bid 4H. It is not without risk, but probably a good guess.
Since responder is a passed hand, a bid of 3H would not be forcing.
When partner bids over an opponents 3-level preempt, a bid by an unpassed responder is forcing.
This needs to be discussed thoroughly with partner.
Responder should try to bid "quickly" i.e. fast arrival on expectged game hands.
This, however, leaves a gap in the system. In case responder is very weak, there is no way to show it.
That is unlikely on the auction, but needs to be discussed with partner.
There are some other ways of handling responses, like the two-trick rule, but that puts more pressure
on the opener.
7 4 2
K Q 9 8 4
5 4
Q J 9