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Say I have a raster with attribute values over some spatial area.

Also, say I have circular polygons of varying sizes contained within the raster's area.

What would be the proper method to test if the raster attribute values contained within a polygon are statistically different from raster attribute values in other polygons?

I first thought to put all raster cell values within polygons into a dataset and test their differences with a t-test, however, it doesn't seem proper to treat each raster cell as an "observation". The t-test would have far too many observations in each polygon and would give the test unwarranted statistical power.

Are there any proper methods for performing such a hypothesis test?

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  • You did not state any software you use. I added an answer for QGIS and added this as tag as well.
    – Babel
    Jul 2, 2021 at 20:53
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    I think my question pertains to the specific spatial statistical method, rather than the software.
    – geoscience123
    Jul 2, 2021 at 20:53
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    Treating each circle as an observations would seem more reasonable. You could take the average of the raster cells covered by each polygon.
    – Robert Hijmans
    Jul 3, 2021 at 2:44

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Zonal statistics is the tool to use for such a purpose, see Zonal statistics documentation for QGIS.

By the way: rasters do not have attributes, but each pixel contains a value (in one or more bands).

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