Re: [Numpy-discussion] Distribution Functions Change Behavior

2008-04-28 Thread Alan Isaac
On Mon, 28 Apr 2008, Hoyt Koepke wrote: > I may not understand what you are asking, Rich, but I'm > not sure I agree with Alan. A Gaussian fit to data > x should fit exactly as well as data fit to ax, a > 0, > just with a variance a^2 times the original My point was different. If you truncate

Re: [Numpy-discussion] Distribution Functions Change Behavior

2008-04-28 Thread Rich Shepard
On Mon, 28 Apr 2008, Hoyt Koepke wrote: > A Gaussian fit to data x should fit exactly as well as data fit to ax, a > > 0, just with a variance a^2 times the original. The only way this would > not be true is if: Hoyt, This is what I expected, too. > 1. You are not fitting the variance, but o

Re: [Numpy-discussion] Distribution Functions Change Behavior

2008-04-28 Thread Hoyt Koepke
Wait, I think I see what Alan is saying. When you use a gaussian approximation on truncated data, the accuracy of the truncation is very dependent on where in the interval the mean is. If it's near the edges, the results will be worse. The width of the interval, though, is a separate factor. --

Re: [Numpy-discussion] Distribution Functions Change Behavior

2008-04-28 Thread Hoyt Koepke
I may not understand what you are asking, Rich, but I'm not sure I agree with Alan. A Gaussian fit to data x should fit exactly as well as data fit to ax, a > 0, just with a variance a^2 times the original. The only way this would not be true is if: 1. You are not fitting the variance, but only

Re: [Numpy-discussion] Distribution Functions Change Behavior

2008-04-28 Thread Alan G Isaac
Hi Rich, If your data is truncated at zero, it is not Gaussian (drawn from a normal). You will notice this when you shrink the range of values (unless the variance is tiny). Cheers, Alan Isaac ___ Numpy-discussion mailing list Numpy-discussion@sci