Fuente: July 2016 ACBL Bridge Bulletin 
Splinter bids, which send a clear distributional message, present a great opportunity to fine-tune your hand evaluation skills. You open l holding:
Opponents silent, partner responds 4, a classic splinter promising a hand worth a game force with at least four-card spade support and either a singleton or void in clubs, the splinter suit. How does the splinter raise affect your slam prospects?
You need help in diamonds; partner has you covered in clubs. Visualize partner’s high-card strength in the red suits – where else can it be? If partner holds the A K, 7 is probable. Initiate a control-bidding sequence to pinpoint location. Let’s say you start with 4 and partner replies 5 , both first-round controls. Continue with 5, first- and second-round control, and if partner responds in kind with 6 , bid the grand slam. At worst you may need a 3-2 diamond division if partner tables:
More often, 7 will be laydown if partner produces either the A or K to provide diamond discards, or the J or A-K-(x). By the way, expect a trump lead because splinter raises deliver ruffing values. That’s an important reason to insist on a fourth trump when using a splinter.
In the next example, partner opens 1 , you respond 1 , and partner jumps to 4, a splinter that shows club shortness, four hearts and a toptier opening. Which would you rather hold?
Both hands contain 8 HCP but are vastly different in value. Hand A demands a slam-try bid of 4, while hand B should sign off in 4. To see why, match each hand to a typical hand for opener:
The diamond fillers in hand A make 6 a huge favorite to lose only one club; just remember to start clubs before drawing trumps in case trumps split 3-1. The club wastage in hand B makes slam impossible. The club royals prove useless – even with the A onside to provide two diamond discards from opener’s hand, declarer is still stranded with a diamond loser.
[box]The moral: Facing a splinter raise, promote secondary honors – kings and queens – in partner’s long suits and demote the same values facing shortness.[/box]
Try another: You open 1, partner splinters to 4 . Which of these two hands is preferable?
Don’t focus on total HCP; focus on the location of honor cards.
Hand C has weak trumps and spread-out values; hand D is concentrated. D is the stronger hand. Again, create a representative hand for partner and visualize the play in a spade contract.
Hand C basically needs a 2-2 spade split, plus the heart finesse, to make slam, roughly a 20% chance. Notice that the K is wasted; one discard from opener’s hand is worthless. Hand D is a big favorite to make 6 ; only the J is wasted. With hand C, sign off in 4.
With hand D, try for slam by bidding 4 , ostensibly a first-round control. However, it is permissible to feign a first-round control below 4NT because partner can use Blackwood to learn the truth. The main point is to appreciate the slam-worthiness of hand D and avoid a signoff.
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