The All In Bluff

I have been conducting an experiment and I have come to the conclusion that when someone goes all-in after the flop they usually have a set or better usually a straight.

I have called about 15 all-in during tournament play just to see what they had. I have lost all of them.  This is not a very large sample size, but it is definitely enough to draw a conclusion that most of the time someone goes all in they have a pretty good hand.

I have also tried bluffing by going all-in, and I have found this is a really good way to lose all your chips.  Somewhere between half and a third of the time someone will call and usually they will have you severely dominated.  I have lost over 75% of the time I have been called.

So I have decided since I usually only get away with it 2 or 3 times at the most then I get knocked out of the tournament bluffing by going all-in is a strategy that need to be used very rarely.  And you probably need to have an idea about he players you are trying to bluff.  

Are they more likely to fold or call, without knowing this you will be out in no time.