A note on calibrating the Neighbourhood Effect (N)

The strength of the Neighbourhood effect (N) depends on the values given to the weights in the matrix that is applied to the land use map with the focal command (see Neighbourhood Dynamics). Clearly, if the weight values applied to N are many times higher than the values that are computed in the Accessibility (A) and Suitability (S) maps, then N will be much stronger that A or S. But in some situations this might not be realistic. For example, if we replace
w <- matrix(c(0,0,50,0,0,0,50,50,50,0,50,50,500,50,50,0,50,50,50,0,0,0,50,0,0), nr=5,nc=5)

with:

w <- matrix(c(0,0,0.5,0,0,0,0.5,0.5,0.5,0,0.5,0.5,5,0.5,0.5,0,0.5,0.5,0.5,0,0,0,0.5,0,0), nr=5,nc=5)

The other parameters (e.g. accessibility, suitability and randomness) play a much larger part in determining the areas that are most likely to change. In this case, it makes for a much more realistic simulation. Compare:

strongN weakN

At left, neighbourhood rules as normal. At right, neighbourhood rules adjusted downwards by a factor of 100.

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