1. Lab: geostatistics Peter Fox GIS for Science ERTH 4750 (98271)
Week 11, Friday, April 13, 2012

2. Statistics http://escience.rpi.edu/gis/data/radon2.xls
The uncertainty in a value estimated by weighted averages is one over the square root of the sum of the weights.
Use IDW to estimate the uncertainties in estimated values at (73.58W, 42.69N), at (73.45W, 42.83N), and at (73.46W, 42.51N)
Hint: week5b slides and Excel for the calculations

3. Statistics
(originally from )
Geocode the table by place names using Rens2000 and common sense.
[You might add the lon/lat to your table…]

4. Statistics
The uncertainty in a value estimated by weighted averages is one over the square root of the sum of the weights.
Use IDW to estimate the uncertainties in estimated values at three different locations of your choosing, e.g. could be a place, street address or just a lon/lat

5. Statistics http://escience.rpi.edu/gis/data/radon3.xlsx
Perform a weighted regression to fit basement radon based on living room radon
Hint: contains all the Excel formulae
Extra: Perform a weighted regression to fit living room radon based on basement radon

6. Recall
Letting x represent the position vector (x, y) and assuming the variances in the differences between any 2 measurements depends only on the distance between them:
E [ { z(x) – z(x+h) }2] = E [ { F'(x) – F'(x+h) }2] = 2 G(h).
G(h) is known as the semivariance
G(h) = (2n)-1 SUM i=1,n { z(xi) – z(xi + h) }2

7. Semivariance
This represents a sum of the differences squared for all pairs of points that are a distance h apart. Typically one calculated G (h) for a range of distances and plots G (h) vs. h.

8. Semi-variance http://escience.rpi.edu/gis/data/radon2.xls
Calculate the semi-variance and plot it
In Excel (not the best way to do it but it will give you the idea)
Calculate Hij=sqrt((Xi-Xj)^2+(Yi-Yj)^2)
Zij=(Z(Xi,Yi)-Z(Xj,Yj))^2
Determine what the range of ‘h’ is and determine a reasonable number of ‘bins’
Then, over all i,j put Zij into one of those bins (to produce the smoothed (or not) curve
Hint, do this for a sub-sample of radon2 to start

9. See the MapBasic program
As an example of what a simpler and basic piece of code looks like.
NB. This has to be compiled to run, it will not work at the MapBasic window command line