Hi Monica, thanks for quick reply. The interpolated data is a different data set with is by its nature (speaking about geological properties) should be correlated with the sparse one. This is a geological data over not huge area - around 20x30 kilometers. It should have at least some spatial correlation. The variogram is not of striking beauty :) but it is not a pure nugget effect, though. The only other way meaningfully interpolate between those sparse points, it seems to use the simple linear regression between those two datasets. The literature about kriging/interpolating for very sparse data would definitely help, if anybody know about, please let know.
Thanks, Gali --- Monica Palaseanu-Lovejoy <[EMAIL PROTECTED]> wrote: > Hi, > > I am not sure i understood correctly your question. > Fist of all, do > the interpolated data have come from your sparse > data > interpolation? What method of interpolation did you > use in this > case? > > After Burrough and McDonnel, 2000, you need at least > 50 points to > have reliable results through kriging. Certainly you > can do it on less > data, but until now i never saw a study considering > this problem in > depth (maybe there is literature out there, and if > it does and > anybody knows about it - i would like to know it > also ;-)) > > Secondly, if you know the outlier is not an error, > but you interpret it > as representing a different combination of > properties than the rest > of your data - i am not very sure it is wise to use > it together with > your rest of the data in any interpolation exercise. > The outlier may > represent a different population and in this case i > cannot see any > "physical" reason to treat all your data together if > parts of the data > represent different things. At least this is my > opinion. > > Besides, if your data is not only sparse (5 or 6 > data points .... it is > really very sparse i think) but also far away in > space, they can be > at distances grater than the spatial correlation > range, and in this > case i really don't think you can use kriging .... > you will have either > a pure nugget effect or a very high nugget value and > not a too high > spatial correlation. > > Monica __________________________________ Do you Yahoo!? Free Pop-Up Blocker - Get it now http://companion.yahoo.com/ -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
