Re: AI-GEOSTATS: Kriging Error vs variance

2003-01-28 Thread Digby Millikan
Donald, Thanks for your reply, my comments; Digby I don't understand some of your comments: 1. Stationarity is not a property of data, it is a property of the underlying random function (no matter which form of stationarity you are considering). + +

AI-GEOSTATS: Kriging Error vs variance

2003-01-27 Thread Russell Barbour
Dear List members, I am looking for a reference on interpretation of the Kriging error versus the sample variance. Am I correct in assumung that in any kriged interpolation where the Kriging error is greater than the sample varience then the sample mean would be a better estimate at that

Re: AI-GEOSTATS: Kriging Error vs variance

2003-01-27 Thread Isobel Clark
Russell Absolutely on the spot. We call this the 'ygiagam' criterion (your guess is as good as mine) ;-) Isobel Clark http://geoecosse.bizland.com/news.html __ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to

Re: AI-GEOSTATS: Kriging Error vs variance

2003-01-27 Thread Pierre Goovaerts
Hi Russell, I am assuming you refer to kriging error variance. If your semivariogram is bounded and has a sill close to the sample variance, then the simple kriging estimate will automatically be the global mean when the kriging variance is the sample variance (that is when all observations are

Re: AI-GEOSTATS: Kriging Error vs variance

2003-01-27 Thread Digby Millikan
You may have to consider the stationarity of your data, i.e. theoretically your sample mean is better than your kriged estimate if your kriginng error is greater than your kriging variance, but you did make the assumption that your data is stationary when you kriged it, i.e. constant mean and

Re: AI-GEOSTATS: Kriging Error vs variance

2003-01-27 Thread Digby Millikan
Russell, If you have time to get to your library there is a book Geostatistical Ore Reserve Estimation 1977 M.David although related to geostatistics for mining this book is written by a renowned geostatistician and has an excellent diagrammatic representation of trend, drift and