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Re: st: n() option for -akdensity-


From   Alfonso Sánchez-Peñalver <alfonso.statalist@gmail.com>
To   Stata List <statalist@hsphsun2.harvard.edu>
Subject   Re: st: n() option for -akdensity-
Date   Tue, 1 Apr 2014 10:54:36 -0400

Forget me if Im wrong because I dont know much about how the adaptive version of a kernel density works (by the way, you should mention that -akdensity- is available from SSC), but the whole point of a kernel density is to use the sample points as kernels and non-parametrically estimate the density function under the assumption that the sample follows the populations distribution. How are you going to use more points than those you have in the data? Are you going to make them up? I may have misunderstood what you meant with larger n, but Im really confused.

Alfonso Sánchez-Peñalver, PhD


On Apr 1, 2014, at 10:33 AM, Katie Farrin <kfarrin@gmail.com> wrote:

> Good Morning,
> 
> I'm trying to estimate a cdf from a kernel density using a data series
> (n=72) I have using the -akdensity- command.  However, I'd like more
> data points in the cdf than I have for actual observations and am
> having trouble using the n() option for -akdensity- and am hoping
> someone can give me some advice on how to create a cdf with a larger
> n.
> 
> I'm plotting the kernel density along with a normal distribution with
> n(500) and would like the same number of data points for the kernel
> and cdf, but I get an error message when I try to specify n in the
> options for the cdf.
> 
> Here is the code I'm using:
> 
> akdensity GC, bwidth(.5) normal n(500) generate(gx_chim fgx_chim)
> cdf(cdf_g_chim)
> line cdf_g_chim gx_chim
> 
> Any help would be greatly appreciated.
> 
> Katie
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