1. Spatial statistics
Topic 4
2/2/2007

2. What is spatial statistics
Not like traditional, a-spatial or non-spatial statistics
But specific methods that use distance, space, and spatial relationships as part of the math for their computations
Is a spatial distribution and pattern analysis tool
Identifying characteristics of a distribution; tools used to answer questions like where is the center, or how are feature distributed around the center? (Measuring Geographic Distributions)
Quantifying or describing spatial pattern; are our features random, clustered, or evenly dispersed across our study area? (Analyzing Patterns)
Mainly deal with point, line, polygon (vector)
Why use spatial statistics?
To help assess patterns, trends, and relationships
Better understanding of geographic phenomena
Pinpoint causes of specific geographic patterns
Make decision with high level of confidence
Summarize the distribution in a single number

3. Measuring geographic (spatial) distribution
Used to
Compare distributions of different features
Identify directional trends of features
Examine changes over time

9. Analyzing spatial patterns
Analyzing Patterns
Global calculations
Identifies the patterns/overall trends of data
Are features clustered and what is the overall pattern?
Spatial Autocorrelation tool
Mapping Cluster
Local calculations
Identifies the extent and location of clustering or dispersion
Where are the clusters (or where are the hot spots)?
Hot Spot Analysis tool

16. Z score is a measure of standard deviation. If you have σ is (-1.96, 1.96), z score is falling between them, you are seeing a pattern of random pattern. If z score falls outside, like -2.5 or 5.4, then you have a pattern that’s too unusual to be a pattern of random chance

18. Followed with a free ESRI video presentation “understanding Spatial Statistics in ArcGIS 9” by Sandi Schaefer and Lauren Scott.