Dear Clement,
Clément Calenge-2 wrote:
>
> However, why do you want to set byburst=TRUE? setting byburst to FALSE
> will allow you to compute one UD per animal (per ID in fact). If the
> time lag between the end location of one burst and the beginning
> location of the next is long enough, this will not affect the estimate,
> because the Brownian bridge connecting these two relocations will be
> more "diffuse".
>
Thank you for your reply. Your comments have been very helpful so far! I
understand from your example that at a larger time lag, there is virtually
no 'bridge' created between the two points. However, I do think that these
extra bridges will affect the overall results for my data set. Looking at
the example data I posted earlier (attached again for convenience; fix rate
of 30 minutes, with "night" clusters separated by about 16 hours), using the
following script (simplified from my earlier post):
data<-read.csv("burst_test.csv")
attach(data)
xy<-cbind(x,y)
da<-as.POSIXct(strptime(as.character(data$datetime), tz="GMT", "%d/%m/%Y
%T"))
trj<-as.ltraj(xy,da,id,typeII=T,slsp="remove")
sig1<-1.0
sig2<-10
asc <- ascgen(xybox, cellsize=25)
bb<-kernelbb(trj, sig1, sig2, byburst=T,grid=asc)
images<-image(bb[[1]]$UD)
the bridge between each cluster is still apparent, and I believe that this
could skew results, particularly when compounded over many days/nights. I
think this is of most concern when looking at the outer contours of the UD
with low probabilities of use, where flattened individual bridges created
between points with lengthy time lags can cause increased spread and
misleadingly extend the outer contours.
What do you think?
Thanks again,
Andrea
--
View this message in context:
http://www.nabble.com/burst-function-in-liker-and-kernelbb-tp21593626p21969154.html
Sent from the AniMov mailing list archive at Nabble.com.
_______________________________________________
AniMov mailing list
[email protected]
http://www.faunalia.com/cgi-bin/mailman/listinfo/animov
