Selected work

Statistics / Spatial

Spatial Statistics of SADC Development Indicators

Spatial autocorrelation and geostatistics across 16 Southern African countries

A spatial-statistics study of regional development. An interactive page computes global and local Moran's I over any of seven World Bank indicators for the 16 SADC countries, with a linked parallel-coordinates plot and map. A separate geostatistics study in R applies variogram modelling and kriging to point-referenced data.

+0.425

Global Moran's I

0.0001

Pseudo p-value

16

SADC countries

Urban population (% of total) across the 16 SADC countries in 2022: global Moran's I tested against 9,999 random permutations over k-nearest-neighbour spatial weights.

Interactive pageOpen full screen ↗

Pick an indicator and year to recompute global and local Moran's I. The parallel-coordinates plot and the map are linked: brushing one highlights the matching countries on the other.

Problem

Development indicators across neighbouring countries are rarely independent: similar values tend to cluster geographically. A table of numbers hides that structure. The questions are whether the clustering is strong enough to be more than chance, and where the local hotspots and cold spots sit.

What I built

The interactive page pulls seven World Bank indicators for the 16 SADC countries and, for a chosen indicator and year, recomputes global Moran's I with its pseudo p-value and a per-country local Moran's I classification. A D3 parallel-coordinates plot and a MapLibre map share a selection, so brushing a band of values highlights the matching countries on the map and vice versa. Separately, a geostatistics study in R uses point-referenced data to fit variograms and interpolate a continuous surface with uncertainty.

Methods

  • k-nearest-neighbour spatial weights over the 16 SADC countries
  • Global Moran's I with permutation inference (9,999 permutations)
  • Local Moran's I (LISA) classifying high-high, low-low and spatial-outlier countries
  • Linked D3 parallel-coordinates plot and MapLibre GL map with shared brushing and selection
  • Separate geostatistics study in R (gstat): empirical variograms and fitted spherical, exponential and Gaussian models
  • Ordinary and universal kriging with leave-one-out cross-validation
  • Conditional simulation to represent interpolation uncertainty

Results

  • For urban population share in 2022 the 16 SADC countries show positive global spatial autocorrelation (Moran's I = +0.425), highly unlikely under spatial randomness (pseudo p = 0.0001 over 9,999 permutations), so neighbouring countries are more alike than chance alone would predict.
  • Local Moran's I resolves that global figure into specific high-high and low-low clusters, with a handful of countries flagged as spatial outliers against their neighbours.

Research context

  • Coursework for a spatial-statistics module. The interactive page is hosted on AWS (CloudFront) with the basemap served through Amazon Location Service; the kriging study uses a separate point-referenced dataset.

Technology

  • R
  • gstat
  • D3
  • MapLibre GL
  • Amazon Location Service
  • World Bank API

Links