[SciPy-user] skew Gaussian distribution
David Goldsmith
David.L.Goldsmith at noaa.gov
Thu Aug 23 14:21:16 EDT 2007
Ah, then I may be able to help you in two ways. First, my Google search
turned up:
http://azzalini.stat.unipd.it/SN/
Visit the "very brief account" link thereon, but also note on the main
page the passage titled "A pioneer" which hints at a possible "physical"
basis for these distributions in nature; I didn't dig any deeper than
that, but it seems worthwhile to assess whether the family of
distributions he is discussing might "properly" represent your
experimental population.
Second, I used to work for an Astronomer/Applied Optics Engineer, and
was thus exposed, albeit superficially, to physical derivations of
empirical optical particle count distributions; I didn't learn enough to
help you, but he probably could - if you're interested, I can forward
you his email, or if your reticent about making a "cold" contact, I can
forward your email to him to see if he thinks he can help.
DG
Gary Pajer wrote:
> On 8/23/07, *David Goldsmith* <David.L.Goldsmith at noaa.gov
> <mailto:David.L.Goldsmith at noaa.gov>> wrote:
>
> Please educate me: what are a "skew" and "kurtotid"
> Gaussians? (What I
> learned: Gaussians are - by definition - devoid of any
> higher-than-second moments; wouldn't (shouldn't) a "Gaussian" with
> higher-than-second moments be called something else entirely?)
>
>
> Exactly. So I could rephrase my question: what is the name of the
> distribution that is similar to a normal distribution, but has a
> variable amount of skewness? Or is such a distribution a special
> case of one of the many distributions in scipy?
>
> I *think* the pdf of a "skew normal" should be proportional to
> exp(-a*x**2 - b*x**3) but that comes from a quick google search.
>
> Better yet: what I'm trying to do is simulate the spectrum of an
> optical emitter that I have. The spectrum is nearly normal, but it is
> not symmetric. I'm looking for a model distribution. I started by
> looking for something quick and dirty. If "quick" doesn't happen, I
> might actually have to figure out if there is already a
> theoretically-expected distribution for my case. But in the meantime,
> quick and dirty still sounds good.
>
> That's the real question.
>
> thanks for helping me express what I want :)
> -gary
>
>
>
> DG
>
> Gary Pajer wrote:
> > Do any of the distributions in scipy.stats make a skew Gaussian?
> > Ditto, a Gaussian with kurtosis?
> >
> > thanks,
> > -gary
> >
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