Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-05-01 Thread Chuck Ehlschlaeger
Dear Syed, et al., I did much of what you described in the GRASS GIS a while back. (GRASS is public domain, not commercial, but it is a very good GIS.) The title of the paper is "Visualizing Spatial Data Uncertainty Using Animation" and a copy of it is located at: http://www.geo.hunter.cuny.edu/

Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-30 Thread Chaosheng Zhang
Dear all, Thanks for so many interesting replies and thoughtful discussion. This is not a summary yet, as I am expecting more to come. Just to express my feeling about Indicator Kriging. To produce a probability map, IK might be one of the choices. However, I always feel that too much informatio

RE: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-29 Thread Syed Abdul Rahman Shibli
>From: "McKenna, Sean A" <[EMAIL PROTECTED]> > >1) When trying to explain the concepts of spatial variability and >uncertainty, we have found that showing example realizations of what the >possible distribution of contaminants could look like provides the groups >involved to get a more intuitive

RE: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-29 Thread McKenna, Sean A
MS 0735 Albuquerque, NM 87185-0735 ph: 505 844-2450 -Original Message- From: Chaosheng Zhang [mailto:[EMAIL PROTECTED]] Sent: Monday, April 29, 2002 3:57 AM To: Pierre Goovaerts Cc: [EMAIL PROTECTED]; Dave McGrath Subject: Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation? Pierre,

Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-29 Thread Pierre Goovaerts
Hi Brian, One hundred realizations are typically generated mainly for CPU reasons. You are perfectly right that this number is too small when looking at small probabilities like 0.05 or 0.01. It's why I wouldn't recommend using stochastic simulation to derive probability of occurrence of events a

Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-29 Thread Brian R Gray
I am curious about the use of 100 realizations to generate a probability map. is this a standard approach? if so, is a "small" p-value (such as .05) used? if so, it would seem like 100 iterations might be a smallish sample size for distinguishing, say, .05 (ie 5 outcomes out of 100) from, say,

Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-29 Thread Chaosheng Zhang
erts" <[EMAIL PROTECTED]> To: "Chaosheng Zhang" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]>; "Dave McGrath" <[EMAIL PROTECTED]> Sent: Saturday, April 27, 2002 4:53 PM Subject: Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation? > Hello,

Re: AI-GEOSTATS: Risk Assessment with Gaussian Simulation?

2002-04-27 Thread Pierre Goovaerts
Hello, In the past few years stochastic simulation has been increasingly used to produce probability maps. To my opinion it's generally a waste of CPU time since similar information can be retrieved using kriging, either in a multiGaussian framework or applied to indicator transforms. The issue o