AI-GEOSTATS: Extreme values?

2001-12-13 Thread Chaosheng Zhang
Dear all,   My question is: How to deal with the extreme/outlying values in a data set?   I am dealing with heavy metal concentrations in soils from a mine area. The sample number is 223, and the samples are spatially evenly distributed with the sampling interval of 400 metres. There are sev

Re: AI-GEOSTATS: Extreme values?

2001-12-13 Thread Isobel Clark
> My question is: How to deal with the > extreme/outlying values in a data set? The real priority is to establish why you have extreme highs. For example: (1) is there a high imprecision in measuring the values, so that the sample observations are actually inaccurate? If so, is it relative to the

Re: AI-GEOSTATS: Extreme values?

2001-12-13 Thread Chaosheng Zhang
Dear Isobel, Thanks for your quick and helpful reply! (1) I would like to trust both the accuracy and precision of the dataset, and the real problem is how we "play the computer game". The extreme values may be from the samples which by chance contains many minerals. (2) From the information of

AI-GEOSTATS: interannual spatial "stability" of variable

2001-12-13 Thread Chris Duke
Hi, we have multiyear point data (gridded) of a measured variable, Y, from farm fields and there are spatial patterns to Y. We want to measure the degree of similarity of these patterns from year to year. Could someone please point me in a direction or provide references? thanks, chris -- * To

Re: AI-GEOSTATS: interannual spatial "stability" of variable

2001-12-13 Thread Isobel Clark
Chris There are two ways of approaching data which has a time element: (1) treat time as a co-variable and use co-kriging. You would probably want to do this if you have more than one variable anyway (2) treat time as a dimension -- as an additional co-ordinate. If your original data is two-dim

Re: AI-GEOSTATS: Extreme values?

2001-12-13 Thread Marcel Vallée
Dear Chaosheng Zang The sampling interval is so wide that the high values could easily be related to "hot spots" of higher grade contamination, i..e dumping areas for particular kinds of slags, mineralized waste, etc. A property map might help. Have you contoured the data? If so, the samp