Documentation does not specify how input coordinates should be formatted/ distance is calculated for modified test.

[raholler]

modified.ttest gives different results when different coordinate formats are used and it is unclear what would be the most correct one because it is not specified how distances are calculated. In particular, it is unclear whether I can use LAT/LON or whether I need to use a project coordinate system to get accurate results.

[faosorios]

Dear Radost,

I appreciate your message and your interest in SpatialPack. Like many statistical tests, the modified t-test is not invariant to changes in scale. This is a quite natural aspect that one should be aware of. I can say that the calculation of the distances between coordinates is performed using the Euclidean distance. I regret that I cannot say if there is any particular choice of type of coordinates that might be more advisable, however, I agree that these details should be pointed out in the reference manual.

Warm regards,
Felipe