All Questions
22 questions
1
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1
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142
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Declustering spatial data and kriging
I am doing a simple project on a mining dataset and came across some problems:
Should I use the declustered values to model the variogram?
Do I apply ordinary kriging to the original or to the ...
0
votes
0
answers
76
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What am I not understanding about semivariogram and Normal Score Transformation?
I have generated this two dimensional random field:
This is done following this page. In particular, I have selected t=23 as dataframe and I have changed some parameters.
As you can noticed, I have ...
- 111
1
vote
1
answer
97
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Generate a syntetic log-normal two dimensional random field
I would like to test some functions that I wrote related to the kriging applied to rain data. In order to do that, I would like to generate a synthetic log-normal 2D random field.
The idea is to ...
- 111
1
vote
0
answers
273
views
Interpreting a Distance & Time 3D Variogram for Variogram modeling
I am trying to understand some concepts of variograms. I have made several variogram models in R and am trying to understand exactly what they mean. My data is ...
- 181
1
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0
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239
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Variogram fit in R not converging
I have taken a shapefile from Open NYC Data and performed the following method. My end goal is to predict Taxi trip_duration at various points across the city of ...
- 181
0
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0
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33
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Why do you need a variogram for Kriging? goldingn/gpe package?
I am using golingn/gpe (github) package, and it does not provide a variogram and instead look at co-variances.
Is it possible to do kriging without providing variograms?
- 1
1
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0
answers
183
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Cokriging, zero distance semivariance [gstat]
Trying cokriging with simulated data, I faced a problem that did not seem one in the demo(cokriging) with the meuse dataset:
I can't use ...
7
votes
2
answers
11k
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What is the nugget effect?
I don't understand exactly what is meant by the term "nugget effect" in geostatistics. When looking at empirical variograms plotting the variogram $\gamma(h)$ vs. the lag $h$, the nugget is defined as ...
- 3,086
0
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1
answer
352
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How do you interpret this variogram?
Description:
8000 spatial data points spanned over an entire state
200 bins are used
My question: Is the variogram telling something about the nature of the data? Why is it fluctuating? Should I do ...
1
vote
0
answers
834
views
Spherical vs. Exponential Kriging Covariance Functions
A statistical epidemiologist colleague of mine told me that in comparing spherical vs exponential kriging covariance functions, only the latter (i.e., exponential) function is generally a valid model.
...
- 1,649
0
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0
answers
92
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Explain Like I'm Five version for Variograms in R's gstat package
Long story short, I asked a question on StackOverflow about Variograms in the gstat package in R. The person who answered gave me some tips on creating the variogram using the package.
My dataset is ...
- 325
4
votes
1
answer
719
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Why is positive definiteness necessary for kriging?
I understand from wikipedia that a variogram model must be positive definite to be used for kriging:
Note that the experimental variogram is an empirical ...
- 2,309
0
votes
0
answers
34
views
Is there a way to find optimal sensor node locations in a domain when all data is known?
I have an x-y domain where I know the snow depth everywhere. (i.e. the granularity of the values is such that I can assume I know it everywhere).
I want to use this information to inform where to ...
- 2,309
1
vote
1
answer
344
views
Kriging: fit.method and dX argument in variogram
I would like to krige residuals (from multiple linear regression) of yearly precipitation totals from a 50 years time series. Every year has been regressed individually. The residuals will be added to ...
- 11
3
votes
1
answer
579
views
Gstat: Modelled semivariogram values not matching plotted model using the variogramLine function
I am trying to extract the semivariance values associated with a given semivariogram model developed in gstat, the end goal being to compare modelled semivariance with observed semivariance at defined ...
- 33
0
votes
1
answer
1k
views
Simple Kriging with linear semivariogram
While studying how to develop a simple kriging model with a linear semivariogram, the various tutorials point towards creating a covariogram using $\sigma(h) = \sigma(0) - \gamma(h)$, but the value of ...
- 101
3
votes
0
answers
519
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Universal kriging: which variogram to use?
I am working with the build in dataset meuse, which has 155 measurements of Zinc and the distance to the river "Meuse".(http://rspatial.r-forge.r-project.org/gallery/).
Now I am trying to imitate ...
- 3,489
1
vote
1
answer
507
views
Kriging results are too localized, how can I increase the influence of each data point
I have a small dataset that looks like this...
...
- 11
1
vote
1
answer
1k
views
R Error in chol.default(A) krigeST from gstat package
I am working with an hourly dataset of air temperature, recorded at ~200 stations over a relatively small area. I chose a space-time variogram (e.g. sum-metric) to fit my data and am now trying to ...
1
vote
0
answers
144
views
Details on kriging and variograms
I was wondering what are the steps to perform factoring kriging. I know it is used to extract specific components that may have a physical meaning and this is achieved by kriging. However, I have some ...
- 3,361
1
vote
0
answers
395
views
Deriving the ordinary kriging equations with noisy data
I am trying to derive the ordinary kriging equations when I want to estimate the underlying value at $T(x_0)$ from the noisy observations at its neighbors $Z(x_1),....Z(x_n)$.
$Z(x_0) = T(x_0) + \...
- 6,847
1
vote
0
answers
111
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Confusion related to ordinary kriging
I was reading this wiki article related to ordinary kriging where they calculated the weights like this
I know that covariance from the covariogram and semivariance from the semivariogram are ...
- 6,847