The methods range from basic to complex, requiring partners to have the same understandings and agreements about their application in their bidding system.
Although 'Robertson's Rule' for bidding (the 7-5-3 count) had been in use for more than a dozen years, McCampbell sought a more "simple scale of relative values.
Called the Milton Work Point Count when popularized by him in the early Thirties and then the Goren Point Count when re-popularized by Work's disciple Charles Goren in the Fifties,[1] and now known simply as the high-card point (HCP) count, this basic evaluation method assigns numeric values to the top four honour cards as follows: Evaluating a hand on this basis takes due account of the fact that there are 10 HCP in each suit and therefore 40 in the complete deck of cards.
The combined HCP count between two balanced hands is generally considered to be a good indication, all else being equal, of the number of tricks likely to be made by the partnership.
[3] Although mostly effective for evaluating the combined trick-taking potential of two balanced hands played in notrump, even in this area of applicability the HCP is not infallible.
In this case, the difference in trick-taking potential is due to duplication in the high card values: in the bottom layout the combined 20 HCP in spades and diamonds results in only five tricks.
The 4-3-2-1 high card point evaluation has been found to statistically undervalue aces and tens and alternatives have been devised to increase a hand's HCP value.
Marty Bergen claims[8] that with the help of computers, bridge theorists have devised a more accurate valuation of the honors as follows: Note that this scale keeps the 40 high card point system intact.
Bergen's “computer” scale appears to be identical to the “high card value of the Four Aces System” found on the front inside cover and on page 5 of the 1935 book, The Four Aces System of Contract Bridge[9] by (alphabetically) David Burnstine, Michael T. Gottlieb, Oswald Jacoby and Howard Schenken.
In order to improve the accuracy of the bidding process, the high card point count is supplemented by the evaluation of unbalanced or shapely hands using additional simple arithmetic methods.
[2][3][10] Accordingly, in a method devised by William Anderson[11] of Toronto and popularized by Charles Goren,[12] distribution points are added for shortage rather than length.
The basic point-count system does not solve all evaluation problems and in certain circumstances is supplemented by refinements to the HCP count or by additional methods.
The use of control count addresses the fact that for suit contracts, aces and kings tend to be undervalued in the standard 4–3–2–1 HCP scale; aces and kings allow declarer better control over the hands and can prevent the opponents from retaining or gaining the lead.
Hands with the same shape and the same HCP can have markedly different slam potential depending on the control count.
The interpretation of the significance of the control count is based upon a publication by George Rosenkranz in the December 1974 issue of The Bridge World.
Despite the spade suit fit, both East hands have marginal slam potential based on their 16 HCP count alone.
On the top layout the control-rich East (an upgraded 17–18 HCP) should explore slam and be willing to bypass 4♠ in doing so, whilst on the bottom layout the control-weak East (a downgraded 12–13 HCP) should be more cautious and be prepared to stop in 4♠ should further bidding reveal West lacking a control in diamonds.
Certain combinations of cards have higher or lower trick taking potential than the simple point count methods would suggest.
This method is particularly useful in making difficult decisions on marginal hands, especially for overcalling and in competitive bidding situations.
In lieu of arithmetic addition or subtraction of HCP or distributional points, 'plus' or 'minus' valuations may be applied to influence the decision.
If the same cards are randomly scattered through different suits, they are about equally likely to take tricks in attack or defence.
Paraphrasing Crowhurst and Kambites (1992), "Experts often sail into an unbeatable slam with only 25 HCP whereas it would never occur to most players to proceed beyond game".
For example, holding ♠ K109864 ♥ A43 ♦ KQ8 ♣ 4 with the auction shown on the left, they point out that the bidding indicates at least 6/3 in spades and 5/3 in diamonds.
At lower levels it is harder to be as precise but Crowhust & Kambites advise "With a good fit bid aggressively but with a misfit be cautious".
The "losing-tricks" in a hand are added to the systemically assumed losing tricks in partners hand (7 for an opening bid of 1 of a suit) and the resultant number is deducted from 24; the net figure is the number of tricks a partnership can expect to win when playing in the agreed trump suit.
Thus following an opening bid of 1♥: Thinking that the method tended to overvalue unsupported queens and undervalue supported jacks, Eric Crowhurst and Andrew Kambites refined the scale, as have others: In his book The Modern Losing Trick Count, Ron Klinger advocates adjusting the number of loser based on the control count of the hand believing that the basic method undervalues an ace but overvalues a queen and undervalues short honor combinations such as Qx or a singleton king.
Main article New Losing Trick Count Extending these thoughts, most experts agree that basic LTC undervalues Aces and overvalues Queens.
Similar to basic LTC, users may employ an alternative formula to determine the appropriate contract level.
Hands with relatively solid long suits have a trick taking potential not easily measured by the basic pointcount methods (e.g. a hand containing 13 spades will take all 13 tricks if spades are trumps, but will only score 19 on the point count method, 10 HCP + 9 length point).
He advises that "your hand is worth an invitation to game (or slam) if this perfect minimum holding for partner will make it a laydown".