[R-sig-Geo] Isotropic edge correction unbiasedness

[Nick Eubank]

Great, thanks so much for taking the time to answer this Adrian! And for
the book link!

On Wed, Jul 27, 2016 at 3:25 AM Adrian Baddeley <
adrian.baddeley at curtin.edu.au> wrote:

> Nick Eubank writes:
>
>
> > Using `kest` to estimate a ripley's K for a country.
>
> This is a question about the 'spatstat' package.
> The function name is 'Kest'.
>
> > The authors of the package suggest isotropic is best when
> computationally tractable for
> > irregular shapes, but I noticed in Ripley (1988) that this correction is
> > only "unbiased provided E is convex", where E is the boundaries of study.
>
> This is covered at length in Chapter 7 of the 'spatstat book'
> <
> https://www.crcpress.com/Spatial-Point-Patterns-Methodology-and-Applications-with-R/Baddeley-Rubak-Turner/p/book/9781482210200
>
> The isotropic corrected estimate is unbiased for all r < R, where R is the
> radius of the smallest circle that encloses the entire window (assuming the
> window is connected).
>
> > With that said, the picture in Ripley (1988) illustrating this correction
> > is NOT convex (it's a kidney shape).
>
> So the statement above applies to this window.
>
> > I know this isn't quite an "r-implementation" question, but: anyone know
> if
> > isotropic correction is unbiased for an odd shape like a country-outline
> > (in this case Sweden)? Or should i use the `border` correction?
>
> Use the isotropic correction.
>
>
> Adrian Baddeley
>
>
>
>

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