Let's take a look at a traditionally difficult (for the most psychologically) bidding decision: should one, playing with IMP-scoring, double a contract that will certainly go down a lot (or can go down a lot, provided that partner finds the right lead) if there is a risk that the opponents escape to a makable contract? (Playing with MP-scoring, the question applies too, if the contract is expected to go only one or two down; in that case there is a second risk: the double warns declarer who may subsequently even make the contract).
The argument in favour of the double: why scorn a juicy +500 or +800 and be satisfied with a mere +150 or +200? Often the opponents do not have an escape available. And even if they have, they will often stay put, afraid of going out of the frying pan into the fire. (Playing with MP-scoring a double can even be necessary if +200 scores a top and +100 a bottom; not doubling can be very costly then, if it turns out declarer cannot avoid going down one).
The argument against doubling is the 'bird in the hand'-principle: just take the plus score instead of doubling greedily and noting something like −1190 a little later (of course real men double them in their escape as well...).

E/NS
♠	K J 10 6
♥	A J 9 8 6 5
♦	Q
♣	8 7

¹ Solid unknown seven-card suit

To double or not to double? Decide for yourself before reading on.

West can see from his hand that his partner has a solid club suit. Probably NS have a good diamond fit then. It is reasonable for West to assume that NS probably cannot make 5♦, since West himself has defensive values in spades and East has the club suit. Perhaps 5♦ will not go down a lot, but they haven't bid it yet! And by passing 4♥, EW will not obtain a huge score.
So Rodwell doubled. He turned out to be both wrong and right...

E/NS		♠	5 2
		♥	—
		♦	A J 10 8 7 4 2
		♣	J 10 6 4
♠	K J 10 6			♠	9 8 7 4
♥	A J 9 8 6 5			♥	4
♦	Q			♦	6
♣	8 7			♣	A K Q 9 5 3 2
		♠	A Q 3
		♥	K Q 10 7 3 2
		♦	K 9 5 3
		♣	—

He was wrong since NS could make 6♦...
But that hardly worried Rodwell, since his double was followed by three passes. South (Stansby) declared skilfully in 4♥ doubled and managed to come out only down three: +800 to EW.
It is hard to say whether NS can be reproached for their bidding. North's pass doesn't look very well-judged but double dummy it is easy to criticise. After all, it looks like South could have had a longer heart suit, meaning West could have doubled on general strength only, including the ♦KQ for instance. Still that argument is dubious: bidding over their pre-empt shows a good hand, points therefore; a long suit alone is not enough. If so, West cannot have a lot of points, North can see from his hand. So perhaps North can deduce West is doubling on hearts mostly...
At the time the critics mostly targeted South, by the way: he could have doubled instead of bidding 4♥. If necessary he could have bid hearts in the second round, showing a hand suited to play in more than one suit (and not necessarily extra strength; this is different from a take-out double at the one level). North might then even, depending on how the auction developed, have bid 6♦.

At the other table Freeman-Nickell (USA 2) in NS did a fine job by bidding 6♦ over East's 1(!)♣ opening. USA 2 won 20 IMPs on the deal (meaning that 6♦ must have been doubled, since undoubled the profit would have been 19 IMPs). The team went on to win the semi final by 276-157 IMPs.
Both teams were defeated next: USA 1 in the battle for the bronze against Norway; USA 2 in the final against France.

We move to Memphis, where the 2004 USBF Championship decides which US team plays in the World Championships 2005. One semi-final sees the clash between teams Nickell and Meltzer. Again we see Chip Martel and Lew Stansby as NS, this time playing on team Meltzer. And again they play Nickell et al.
Paul Soloway (team Nickell) holds as East:

E/—
				♠	A 7
				♥	K J 9 8 6
				♦	7 5 2
				♣	J 10 4

Soloway doubled, hoping for NS to sit tight. That double turned out to be too risky, since East lacked defensive values in two suits. The bidding went on like this:

E/NS		♠	6 3
		♥	A 3
		♦	A K Q 3
		♣	A Q 8 5 2
♠	Q J 10 9 5 4 2			♠	A 7
♥	10 2			♥	K J 9 8 6
♦	9 8			♦	7 5 2
♣	K 9			♣	J 10 4
		♠	K 8
		♥	Q 7 5 4
		♦	J 10 6 4
		♣	7 6 3

Martel, North, had been in a fix after West's 3♠ opening and decided for a dubious double (but what is his alternative?). He caught East's lifeline (the penalty double of 4♥) by way of his smart 4♠ bid. This gave his partner the choice between 4NT to play (if he had a spade guard) and five in a minor. (It looks as if North might have bid 4NT as well. However, South then wouldn't have known whether he could pass. Furthermore: 4NT might have been in the wrong hand then.)
Stansby had no problems in declaring 4NT. The ♠Q lead went to East's ♠A. Declarer won the spade continuation, cashed the diamonds, finessed for the ♣K, cashed the ♣A and played a club, thus rubbing salt in Soloway's wound: East was endplayed with that club and had to underlead his ♥K, giving declarer an overtrick.

Soloway's double cost his team (Nickell) 8 IMPs, where passing would have gained 6 IMPs, since at the other table North (Rodwell) passed the 3♠ opening by West (Sontag). After two more passes, West ended up down two in 3♠.
Despite this deal team Nickell won the semi-final and later the final as well.

Click here to read the second part (out of three parts) of 'Penalty double or pass'