Hi,
I am trying to perform regression kriging in ArcMap. Is there way to do this in ArcMap? Will appreciate any input!!!
Thanks in advance
Hi Eric,
Thanks for your reply. Yes, I have point data. Based on your suggestions, I did the followings:
I am afraid I am still not quite clear what you meant by “plug the results into the OLS equation to get the predicted values”. Is it the last step that I will get my prediction map? Can you please elaborate more? My guess was to add the interpolated independent variable and residual surfaces together, which I did, but predicted values are way too high and have negative values.
It would be very nice to have access to EBK Regression Prediction. Please help me find it if it becomes available.By the way, do I have to pay this new product?
Much appreciate your help!
Roni
There is an issue in your third step. I'm assuming that your dependent variable and independent (explanatory) variables are coming from fields in a point feature class.
In this setup, there is no "correct" way to produce a prediction surface. The explanatory variables must be measured in every location where you want to make a prediction. I understand that this is often impractical, and what is often done in this case is to interpolate the explanatory variables. It is not a good idea to interpolate the predicted values because you know that they depend on the explanatory variables. However, when you interpolate the explanatory variables, all subsequent analysis will assume that the interpolated values are measured values when, in fact, they are predictions and have associated error.
In your case, you need to calculate the OLS equation from the input points, then interpolate the independent variables and the residuals, and plug the results into the OLS equation to get the predicted values.
Regarding cross validation, only the residuals (error terms) are needed. When you are interpolating the residuals, note the cross validation statistics. These are what you should report as the cross validation statistics for the regression kriging model.
However, as I alluded to in my first post, we are releasing "EBK Regression Prediction" in ArcGIS Pro 1.2, which does a regression kriging interpolation using Empirical Bayesian Kriging. It will very shortly be available as a Beta through Esri's customer care website. I am not sure exactly where to go to download it, but I can find out if you are interested.
Hello Eric,
I am trying to carry out a regression kriging analysis for my groundwater project, but I am not sure if my approaches are correct and struggling to calculate RMSE and ME. Can you please give me some comments?
I have groundwater level(n=124) as dependent variable, elevation, temperature, precipitation and NDVI as independent variables.
1.run OLS in Geoda, the Moran`s I test showed that residuals are spatially autocorrelated
2.populate predicted values and residuals back to the groundwater layer
3.use ordinary kriging to interpolate the predicted values and residuals separately
4.convert the output interpolated surfaces to raster
5.use "Plus" tool in Raster to add the interpolated predicted values and residual raster together
thanks so much in advance,
It depends on what kind of regression kriging you want to do. If the explanatory variables are polynomials of the (x,y) coordinates, we call that Universal Kriging, and it is available in the Geostatistical Wizard.
If your covariates are not (x,y) polynomials, you can use the Ordinary Least Squares tool to create a regression equation, and then you can perform kriging on the residuals. To get predictions, add the interpolated residuals to the prediction from the OLS model.
Ideally, the kriging parameters and the coefficients from OLS will be calculated simultaneously (rather than doing OLS then doing kriging), but there is currently no way to do this in ArcGIS. Though that will likely change in the not-so-distant future.
What about Cokriging?
It is currently under development.
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