Atlas · Angola / Methodologies
METHODOLOGIES

Spatial statistics: Moran's I and Getis-Ord Gi*

How clustering and hot spots are detected.

Method

Mangrove area is summed on a 0.05° grid and transformed with ln(1 + ha). Neighbours use queen contiguity (8 surrounding cells).

Global Moran's I tests whether neighbouring cells are similar; significance uses the normal approximation z = (I − E[I]) / SD[I].

Getis-Ord Gi* gives a z-score per cell; |z| ≥ 1.96 is significant at 95% and |z| ≥ 2.58 at 99%.

Limits. No correction for multiple testing is applied; treat marginal cells with caution.

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