P.S. Re: [ai-geostats] Regression vs. Kriging vs. Simulation vs. IDW

2005-01-03 Thread Gali Sirkis
When comparing kriging versus regression, I meant using linear regression between sparse and exhaustive datasets to interpolate the sparse one, since as Digbi Milligan pointed out in general case regression is not an estimation method. --- Gali Sirkis [EMAIL PROTECTED] wrote: Seumas, see

[ai-geostats] sampling density

2005-01-03 Thread Mahdi Osman
Hi, members, I am estimating nitrogen mineralisation rate on a 25 X 25 ha field. One of my efforts is to find out optimum sampling density to examine nitrogen mineralisation in my plot. How can I exploit a semivariogram to answer this question? Does anyone have suggestions and also some relevant

[ai-geostats] sisim and SK vs. OK

2005-01-03 Thread ewbhark
Hello all. I'm performing unconditional sequential indicator simulation over a 3D domain. As the method requires, I have specified the data cdf at (10) thresholds, and have also defined parameters for an (exponential) variogram at each threshold. When I run the simulation algorithm using

Re: [ai-geostats] sisim and SK vs. OK

2005-01-03 Thread Pierre Goovaerts
Hi Eric, I am guessing that the sampling density in 3D is small, hence at the beginning of the simulation procedure when the grid is essentially empty the estimate depends mainly on the type of trend model you adopt, i.e. a global mean for SK or a locally re-estimated local mean for OK. It looks

Re: [ai-geostats] Regression vs. Kriging vs. Simulation vs. IDW

2005-01-03 Thread Volker Bahn
Hi all, picking up on Jeff's point about collocated cokriging: what is the difference between this technique (which I'm not familiar with) and an autoregressive regression models such as CAR, SAR etc? Thanks Volker ___ Volker Bahn Dept. of Wildlife Ecology -