How can I perform Proportional Stratified Random Sampling of the raster with 5 different classes in R software? I tried 'simple Stratified' function, but the output was not proportional because the classes are not of an equal size?
e.g.
?draw
in library(simFrame). You can define the sample sizes here (proportionally).
Also package sampling should have functions to select a proportional to size sample.
Stanley -
Do you want proportional allocation, or optimal allocation? Neyman allocation? Is this continuous data? You need to know something about variance of perhaps a preliminary sample, with regard to the strata, for optimal stratification.
You could try a textbook such as
Cochran, W.G.(1977), Sampling Techniques, 3rd ed., John Wiley & Sons.
or
Lohr, S.L.(2010), Sampling: Design and Analysis, 2nd ed., Brooks/Cole.
Those should have sections that will address your project, I think, but I have never dealt with raster data, and there may be some special considerations.
Sorry. Don't know about R, but I did see a comprehensive looking manual on an Internet search recently.
Cheers - Jim
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