Pearson correlation in raster datasets

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09-27-2010 07:51 AM
AlanFernandes
New Contributor
Dear all,

I need to make a correlation between two raster datasets. I want to use Raster Calculator, but I'm still finding a bit difficult to work it out. I have the formula from statistics books, and I know that I'm required to multiply, and add the grids, right? But it's not so straight forward.
How am I supposed to find N, for instance? Should I just multiply the Columns and Rows from my grid to see how many pixels I have on the dataset?
The formula for the Pearson correlation coefficient is quite long and I don't think I should attempt to do everything in one go. I reckon I should do it by different stages.
Any ideas would be very welcome!

Just a couple more things about the two datasets: one of them is a NDVI that I acquired from LANDSAT 5TM, and the other raster has been originated from an interpolation of points (rainfall gauges). I have used Mask on both grids, therefore they have the same number or rows and columns (same number of pixels?).

Thanks for your time.
Alan.
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11 Replies
JessicaBerryman
New Contributor
What is the difference between using the above procedure and using band statistics to calculate the correlation between rasters?  I am hoping to find the correlations between my environmental variables prior to further analysis in maxent.  Any thoughts would be greatly appreciated.
    Thanks,
         Jessica
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SarahPene
New Contributor
Like Jessica I am also trying to find which of my environmental layers are highly correlated before using them in Maxent. The correlation matrix that it produces has many values outside of the -1 to 1 range, can anyone tell me what the problem is there?  (I'm using the worldclim 1-19 layers, 30arc seconds, clipped to Europe).
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