Let's go back to the first week of July 2011. With the end of QE2 arriving, and no sign of more QE, gold fell to a $1480 low. It then proceeded to blast off over the following 2 months (The only thing that kept it from going all the way to $2000 was when the, ahem, "market" decided that the Swiss Central Bank's decision to print lots of francs was incredibly bearish).
Now, pretend that on the first week of July 2011 you wanted to predict where gold would be on April 1, 2013. You decided to stay on the conservative side and assume that price would increase only linearly and at the same rate it had been increasing since the bull market began in 2001. You would have gotten $1920 as the best prediction for April 1, 2013 (and it doesn't much matter where in 2001 you chose time zero).
Now, pretend that on the first week of July 2011 you wanted to predict where gold would be on April 1, 2013. You decided to stay on the conservative side and assume that price would increase only linearly and at the same rate it had been increasing since the bull market began in 2001. You would have gotten $1920 as the best prediction for April 1, 2013 (and it doesn't much matter where in 2001 you chose time zero).
Well, interestingly, you get essentially the same line today. Meaning, gold should be at $1920 (+/- error). You can't even tell the two lines apart unless you look really closely: one is red, one green. (You can of course fiddle with where to start in 2001 to make them even closer).