Dear Tim, Sorry about my typo. I just want to know what is the unit of variance when the standard deviation has the same unit as the values?
What's the definition of variance actually? Thank you very much! 在 2012年4月24日 下午4:01，Tim Gruene <t...@shelx.uni-ac.gwdg.de>写道： > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Dear Qixu, > > there is no contradiction in your quotes and what you are thinking: > * "The standard deviation has the same unit as the values you're > measuring." > * I always think that the unit of deviation is the same to the values > we're measuring. > > this fits, don't you see? > > Cheers, > Tim > > On 04/24/12 05:21, Qixu Cai wrote: > > Dear Johan, > > > > "the standard deviation is defined as the square root of the > > variance." while "The standard deviation has the same unit as the > > values you're measuring." > > > > So we can say what's the unit of deviation? Is it the square of the > > unit of standard deviation? > > > > I always think that the unit of deviation is the same to the > > values we're measuring. Maybe I make a mistake... > > > > Thank you very much! > > > > > > > > On 04/24/2012 10:30 AM, Johan Hattne wrote: > >> Hi Qixu; > >> > >> This is by definition--the standard deviation is defined as the > >> square root of the variance. > >> > >> http://mathworld.wolfram.com/StandardDeviation.html > >> > >> The standard deviation has the same unit as the values you're > >> measuring, which makes its interpretation a tad easier. > >> > >> // Best wishes; Johan > >> > >> > >> On 23 Apr 2012, at 18:13, Qixu Cai wrote: > >> > >>> Dear Ed, > >>> > >>> Why the variance is the square of standard deviation? > >>> > >>> thank you very much! > >>> > >>> > >>> 在 2012年4月23日，20:53，Ed Pozharski<epozh...@umaryland.edu> 写道： > >>> > >>>> On Sun, 2012-04-22 at 12:47 +0530, Arka Chakraborty wrote: > >>>>> baverage program in ccp4 gave average bfactor of 25.0 for > >>>>> the residue but coot is showing 150! > >>>> Variance is the square of standard deviation, thus var=150 > >>>> means sigmaB~12 in that particular residue. High, but not > >>>> impossible. > >>>> > >>>> -- I don't know why the sacrifice thing didn't work. Science > >>>> behind it seemed so solid. Julian, King of Lemurs > >> Postdoctoral Fellow @ Physical Biosciences Division > >> __________________________________________________________________ > >> > >> > Lawrence Berkeley National Laboratory * 1 Cyclotron Rd. > >> Mail Stop 64R0121 * Berkeley, CA 94720-8118 * +1 (510) 495-8055 > >> > >> > > > > - -- > - -- > Dr Tim Gruene > Institut fuer anorganische Chemie > Tammannstr. 4 > D-37077 Goettingen > > GPG Key ID = A46BEE1A > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.12 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iD8DBQFPll3YUxlJ7aRr7hoRAoOfAJ4kh9s7MryWp9u53dFudMLzbCkT9wCfZ+gV > kTkvc8sma3Z8Ym/9n5JkuOw= > =d+ug > -----END PGP SIGNATURE----- >
