• What is your current elevation? 7000 ft • What if you walked 1 foot away? 7000 ft • What if you walked 100 feet away? 6990 – 7010 ft • What if you walked 1 mile away? 5000 – 8000 ft • What if you walked 100 miles away? 2000 – 14000 ft • Clearly, elevation is spatially-autocorrelated • That is, elevations are correlated with other elevations, and that correlation becomes stronger the closer together the measurements are made • Same is true of many spatial variables: temperature, humidity, slope, aspect, population density, socioeconomics, etc. etc. etc.