diff --git a/content/tutorials/spatial_variograms/index.md b/content/tutorials/spatial_variograms/index.md index 389823215..7f5d01620 100644 --- a/content/tutorials/spatial_variograms/index.md +++ b/content/tutorials/spatial_variograms/index.md @@ -41,7 +41,7 @@ For example: - They [initially](https://en.wikipedia.org/wiki/Variogram#) describe a (semi-)variogram as **"a \[mathematical\] function"**. - That "function" describes the "degree of dependence" of a spatial random field (pro tip: if it is dependent, it is not random, such as the distribution of gold ore used as an introductory example is not random). - As becomes unclear [afterwards](https://en.wikipedia.org/wiki/Variogram#Definition), that function is not "variance" (`var()`), but something else. Although the whole thing is called *variogram*, variance is in fact the "degree of dependence". -- Then, they distinguish an **empirical variogram** ([here](https://en.wikipedia.org/wiki/Variogram#Empirical_variogram)). I would \[refer to\](https://de.wikipedia.org/wiki/Praxis\_(Philosophie%29) the popular philosopher Vladimir Ilyich Ulyanov on this: "Praxis is the criterion of truth"[^1], i.e. there exists no useful *non-empirical variogram*. +- Then, they distinguish an **empirical variogram** ([here](https://en.wikipedia.org/wiki/Variogram#Empirical_variogram)). I would [refer to](https://de.wikipedia.org/wiki/Praxis\_(Philosophie%29) the popular philosopher Vladimir Ilyich Ulyanov on this: "Praxis is the criterion of truth"[^1], i.e. there exists no useful *non-empirical variogram*. - Finally, ["variogram models"](https://en.wikipedia.org/wiki/Variogram#Variogram_models) are mentioned, which are actually *the function* we began with. They are not just one function: there are many options, with the unmentioned Matérn being the generalization for a Gaussian- to Exponential class of functions. My personal definition of the term **variogram** would rather describe it as a moderately flexible algorithm (see box below). @@ -165,6 +165,7 @@ plot(data$x, data$y, col = color, pch = as.integer(18 + 2*data$b)) Figure 1: The raw data, unsmoothed. +
Figure 1: The raw data, unsmoothed.
If you look closely, the upper right is more golden than the lower-left. This is the effect of covariate `a`.