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The Joins Count

Extreme Negative AC

Provides a metric for the correlation among areal units.

Each aeral unit is classified as either black (B) or white (W)

The joins count is determined by counting the number of occurrences in the map of each of the possible joins [BB, WW, BW]

Extreme Positive AC

No AC

Moran’s I

jiij

n

ii

n

i

n

jjiij

wyy

yyyywn

I

1

2

1 1

Moran’s I typically ranges for -1 to 1. An uncorrelated process has an expected I=0. Negative values of I indicate negative autocorrelation. Positive values indicate positive autocorrelation

2000 Presidential Election Results

Adjacency Matrix

149.710

jiij

n

ii

n

i

n

jjiij

wyy

yyyywn

I

1

2

1 1

354.95071 1

n

i

n

jjiij yyyyw

218

jiijw

49n

531.52061

2

n

ii yy

Moran’s I of 0.4 indicates a fairly strong postive correlation between Bush votes in neighboring states

Open P:/arcgis/

Add Spatial Analyst Extension:

1. On Menu Bar: Tools Extensions… Select Spatial Analyst Close

2. On Menu Bar: View Toolbars Select Spatial Analyst

Air Pollution Trajectory Analysis

Residence Time is the amount of time an air mass has spent in a grid cell on it’s way to a particular location.

Res. Times All ConditionsRes. Times High Pollutants

ΣRes. Times High( Σ All Res. Times(( (Incremental Residence Time Probability =