I have a continuous raster that has been divided in 8 zones, and I'd like to compare if the distribution of pixel values in each zone is significantly different from each other. I thought I would use a Kolmogorov-Smirnov test, but I've been advised not to.

Is there a statistical method out there that allow for the multiple comparison of non-normal distributions, without having to create a statistical model of the type Y~X?

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I am not sure why you have been advised to not use the Kolmogorov-Smirnov test. If you put it in the context of a cumulative distribution, and not probability density, function it would likely address your question. Another option are the family of nonparametric t-tests, such as the Mann-Whitney-Wilcoxon test.

You can apply this test using the wilcox.test function in R however, the assumption of the statistic is that the samples come from a distinct population and do not affect each other. Violation of this assumption would be highly dependent on your zones.

  • Thanks Jeffrey. This main assumption seems by essence impossible to meet for spatial data...although the zones have been defined based on their hydrologic behavior and so "hydrologically" disconnected. Therefore, I think they may be considered as independent. Aug 8, 2017 at 19:04

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