What is a 5 Card Suit Worth in a NT Contract?
I often read that a 5 card suit is worth an extra high card point. Users of the strong NT (15-17) will happily upgrade a 14 count because of the presence of a 5 card suit and no other positive features. I have never seen this advised for weak NT users or come across any 11 counts that have been opened as a 12-14 1NT because they have a 5 card suit. Perhaps I should be opening some hands that I currently pass on. This study aimed to find out how valuable a 5 cards suit really is in a NT contract and what makes 5 card suit "good" in this situation.A lot of the problems with double dummy simulations are not so important here because we can look at relative performance rather than absolute performance. If the 3NT contract is reached without any suit bidding then the opening lead could be close to a guess at the table. The double dummy computer will always find the best lead. This could introduce bias if, as is likely, hands with a 5 card suit that is about ready to run will be very sensitive to the choice of opening lead. To reduce this problem, I added analysis where the lead was the defender's longest suit and where just a random card was selected. I looked at the situation of borderline games with fully balance hands (no 5 card suit, no singleton) and 12 points in each hand. Each line in the following table represents the result of 20,000 randomly generated hands.
| Points and Shape | Best Lead | Longest Lead | Random Lead | |||
|---|---|---|---|---|---|---|
| Tricks | % Made | Tricks | % Made | Tricks | % Made | |
| No 5 card suits, 12+12 | 8.09 | 34 | 8.47 | 50 | 8.54 | 52 |
| Semi-balanced, 12+12 | 8.13 | 37 | 8.56 | 53 | 8.65 | 57 |
| No 5 card suits, 12+13 | 8.53 | 53 | 8.94 | 69 | 9.01 | 71 |
| 12 balanced + 12 with 5 card suit | 8.22 | 43 | 8.73 | 60 | 8.85 | 64 |
With 24 points, no 5 card suits and the best lead, it looks like game is not really worth bidding. With a simple lead from the defenders longest suit (a low card or the normal card from a high card sequences), the picture changes and with best play by both sides game is a good chance. This fits in with at the table experience. With 12 points opposite 12, 3NT usually has reasonable chances.
Add one extra point and game needs to be bid even against the best opening lead. This is just the bridge maxim that 25 points is enough for a 3NT game. Leave the points at 12+12 and add a 5 card suit to one hand and the simulations give results about half way to the results for adding a single point. On the surface, this shows that the simple statement that a five card suit is worth a whole point is not true. It could be that a "good" 5 card suit is worth a point, but what makes a suit "good"?
The following table shows the results for a variety of 5 card suits inserted into the 12 point hands. Again 20,000 hands analysed per suit. Clicking the column headers will re-order the table to allow investigation. My conclusions are below the table.
| 5 Card Suit | Best Lead | Longest Lead | Random Lead | |||
|---|---|---|---|---|---|---|
| Tricks | % Made | Tricks | % Made | Tricks | % Made | |
| 65432 | 7.97 | 29 | 8.38 | 43 | 8.51 | 49 |
| J5432 | 8.04 | 33 | 8.48 | 51 | 8.63 | 54 |
| Q5432 | 8.00 | 32 | 8.46 | 49 | 8.61 | 54 |
| K5432 | 8.01 | 34 | 8.53 | 51 | 8.66 | 56 |
| A5432 | 8.07 | 34 | 8.54 | 50 | 8.65 | 55 |
| JT432 | 8.21 | 40 | 8.69 | 57 | 8.84 | 63 |
| QT432 | 8.19 | 40 | 8.67 | 58 | 8.82 | 64 |
| QJT32 | 8.14 | 40 | 8.67 | 58 | 8.81 | 64 |
| KT432 | 8.30 | 44 | 8.81 | 62 | 8.92 | 66 |
| KT932 | 8.38 | 49 | 8.90 | 66 | 9.03 | 71 |
| KQJ32 | 7.96 | 34 | 8.52 | 55 | 8.62 | 60 |
| KQJT2 | 8.04 | 38 | 8.60 | 58 | 8.70 | 63 |
| AT432 | 8.35 | 46 | 8.85 | 64 | 8.97 | 69 |
| AT982 | 8.47 | 51 | 8.97 | 68 | 9.10 | 73 |
| AJ432 | 8.25 | 41 | 8.76 | 59 | 8.86 | 63 |
| AJT32 | 8.49 | 53 | 9.04 | 70 | 9.14 | 73 |
| AJT92 | 8.53 | 54 | 9.09 | 71 | 9.18 | 74 |
| AQT92 | 8.43 | 49 | 8.97 | 67 | 9.06 | 70 |
| AQJ32 | 8.17 | 40 | 8.74 | 59 | 8.82 | 63 |
| AKJ32 | 8.21 | 41 | 8.75 | 60 | 8.83 | 64 |
| AKT32 | 8.32 | 45 | 8.85 | 64 | 8.94 | 68 |
| AKT92 | 8.38 | 48 | 8.92 | 66 | 9.01 | 70 |
| AKQ32 | 8.12 | 37 | 8.64 | 58 | 8.74 | 62 |
| AKQJ2 | 8.17 | 34 | 8.59 | 57 | 8.67 | 61 |
| AKJ32 | 8.21 | 41 | 8.75 | 60 | 8.83 | 64 |
| AQJ32 | 8.19 | 41 | 8.76 | 59 | 8.83 | 63 |
Conclusions
- A really poor 5 card suit does not help, in fact it makes things worse. No upgrade of points here.
- Tens and nines are valuable cards in the 5 card suit, but need top honours for assistance.
- The Ace is a valuable card to have in the long suit. Probably worth counting it as a bit more than 4 points if it heads a 5+ card suit.
- A lot of honour cards in the long suit seem to be bad. This seemed strange at first, but after some thought and looking at some sample deals is not really that surprising.
With only 24 points between the hands, taking out 10 in one suit only leaves 14 for the other 3. With an average of 4.6 points worth of honours in each suit, means it is either not easy
to generate the remaining 4 tricks required, or there is a serious weakness in a suit that the defense can exploit.
- The best 5 card suits are headed by something like A J 10 and are certainly worth a full extra point.