Dear John,
A real life example is available at https://doi.org/10.5281/zenodo.2784012.
The idea is that the database returns a randomised set of points. You need
to overlay these points with your sampling framework. The final sample is
the set of points with the lowest ranking. The grtsdb package
Dear Thierry,
Thank you so much for your reply. Yes, the loss of the spatial balance once
the two-tiered approach is not accounted for was what was worrying me.
The incorporation of region as a random effect has two issues - 1) the
overall sampling area is a lake, and "regions" don't make sense i
Dear John,
Your procedure will create a spatially balanced level 1 sample (10
"regions") and within those regions a spatially balanced level 2 sample.
When you ignore the structure, there is no longer a spatial balance. So
you'll need to incorporate the two level sampling structure in your
analysi
On Thu, 7 Oct 2021, John Wilson wrote:
Oh, sorry - I normally use the grts() function from the spsurvey package.
My hacky approach was to make 10 balanced points with grts(), followed by
imposing a 5 km buffer around each one, and either systematic sampling
within the buffer circle, or running a
Oh, sorry - I normally use the grts() function from the spsurvey package.
My hacky approach was to make 10 balanced points with grts(), followed by
imposing a 5 km buffer around each one, and either systematic sampling
within the buffer circle, or running a separate GRTS for the 5 points
within eac
On Thu, 7 Oct 2021, John Wilson wrote:
Hi everyone,
I'm working on a sampling design using GRTS, but I'm running into a
logistics problem. The field crew can set 5 nets per day, but only within a
5 km stretch, due to travel time constraints. With 10 sampling days, that's
a total of 50 sites. Th
Hi everyone,
I'm working on a sampling design using GRTS, but I'm running into a
logistics problem. The field crew can set 5 nets per day, but only within a
5 km stretch, due to travel time constraints. With 10 sampling days, that's
a total of 50 sites. The overall sampling area is huge, so runnin
