Stoppage time does not match what is stated

As an American trying to learn the game, I have a simple question. When the fourth official states that there are to be so many minutes of stoppage/injury time to play, the whistle is often blown after that many minutes have actually been played. For example, in the Italy World Cup loss yesterday, this was the case. The game continued well after the stated time, almost as if Italy was being granted a chance to catch up.

Is this because the official's watch does not match the scoreboard time? Is this in order to account for injuries/stoppage that occur during injury time? Does the official have the decision to allow play to continue to completion of the final attack?

I'm curious to hear how this works.

Is this in order to account for injuries/stoppage that occur during injury time? Does the official have the decision to allow play to continue to completion of the final attack?

Both of these really. Although the referee doesn't really have to allow completion of the final attack, i guess it depends on how strict they are.

"Is this in order to account for injuries/stoppage that occur during injury time?"

The answer to that is yes and is the answer to your question. Also the stoppage time added in the first place is supposed to be the minimum of time added on and it is at the discretion of the referee to end it when he feels time is up. They generally don't end the match in the middle of an attack though and also if there is a penalty they have to allow time for that to be taken.

Key word as mentioned by Jod is minimum.

The time added on as displayed by the 4th Official on the touchline is the minimum which will be added on.

Yes, that is just the minimum and it is up to the referee, and some like to add more and some don't, it's just personal, as is 'when' they like to blow the whistle.

A few times (in fm), I've had the stoppage time be double what the 4th ref stated. Twice, the opposing team got the tying/winning goal in the extra extra time. Then again, I've had the clock stop exactly on the 93rd minute or whatever even though the other team was counter attacking. They usually do it pretty well in FIFA 10. If you are advancing in the opponents 2/3 of the field and are down by one or tied, they'll let you finish off the attack.

Thanks guys. That's good to understand.