[AniMov] site fidelity test and harmonic mean

Anne Ghisla a.ghisla at gmail.com
Thu Jan 12 15:46:26 CET 2012


On Mon, 09 Jan 2012 10:34:52 +0000
Giovanni Manghi <giovanni.manghi at gmail.com> wrote:

> Hi,
> 
> On Thu, 2012-01-05 at 02:22 -0800, Maximiliano wrote:
> > Hi, 
> > does anybody know if there’s an application of Qgis to perform SITE
> > FIDELITY TEST, like in arcview3?
> > I’d like to know if I calculate the harmonic mean of all my fixes
> > and the distance of each fixes from this “home range” centre…
> > thanks a lot!!
> 
> 
> don't think there is something ready for QGIS, but it would be a nice
> addon for the Home Range or for the triangulation plugin. Any interest
> in supporting its development?

Hello Maximiliano, Giovanni,

the literature on harmonic mean is quite old: the method dates back to
1980 and the Animal Movements documentation [0] warns about the known
problems in home range estimates.

I won't implement this specific method in HomeRange plugin, as I don't
support the idea of implementing a method that has such known biases. 

Also, as HR plugin is a interface to adehabitat, I would ask Clément
Calenge his opinion about adding this method to adehabitat directly.

As an alternative to harmonic means, to individuate the core centres of
the home range, I suggest to calculate homeranges with kernel method and
select the 90% isopleth. (90% is a common value to identify core areas.
However, better run an incremental core area analysis [1] to identify
the correct limit of the core area for each animal). Then, calculate the
center of each core area polygon and use it instead of the harmonic
mean.

This is my suggestion, of course comments and improvements are welcome!

[0]
http://alaska.usgs.gov/science/biology/spatial/gistools/animal_mvmt.php#harm_mean
[1] http://wiki.faunalia.it/dokuwiki/doku.php/public/animove_howto#analyses

Best regards,

Anne
-- 
http://gis.cri.fmach.it/ghisla/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: not available
URL: <http://lists.faunalia.it/pipermail/animov/attachments/20120112/ab777315/attachment.pgp>


More information about the AniMov mailing list