The Learner's Guide to Geospatial Analysis

Fusion

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A matrix with hypotheses across the top and evidence and arguments down the side is developed. Note that your evidence and arguments may or may not be geospatial in nature.

Example Matrix Headers
Evidence/Argument Michael's Employee Foreign Terrorist Serial Killer Domestic Terrorist
1. Conforms to the geospatial model of a serial criminal        
2. All DC-area kilings occured within 30 days        
3. The majority of the shootings were at or near shopping centers        
4. Shootings were all on major highways or interstates        
5. There was only one shooting per location and often occured at gas stations        
6. Sighting of a blue car with two black men        
7. Sighting of a white van with two individuals at one killing        
8. Military caliber weapon(5.56mm)        
9. Noise heard but shooter never seen        

Work down the evidence column and across the rows of the matrix, examining one item of evidence at a time to see how consistent that item of evidence is with each of the hypotheses. Make a notation C, I, and N/A standing for consistent, inconsistent, or not applicable. In this example, the evidence is weighted by using combinations of CC, II, C, and I.

Example Matrix of Evidence and Arguments
Evidence/Argument Michael's employee Foreign Terrorist Serial Killer Domestic Terrorist
1. Conforms to the geospatial model of a serial criminal I C I C
2. All DC-area kilings occured within 30 days C C CC C
3. The majority of the shootings were at or near shopping centers I CC C CC
4. Shootings were all on major highways or interstates I CC CC CC
5. There was only one shooting per location and often occured at gas stations I II CC CC
6. Sighting of a blue car with two black men I I I I
7. Sighting of a white van with two individuals at one killing I C C C
8. Military caliber weapon(5.56mm) C C C C
9. Noise heard but shooter never seen I I CC CC

Analyze the "diagnosticity" of each piece of evidence. We discover that the evidence of the rifle's caliber is not very helpful because it is consistent with all hypotheses. Refine the matrix by reconsidering the hypotheses and delete evidence and arguments that have no diagnostic value. In the case, I deleted the "Military caliber weapon (5.56mm)" evidence since it offered no diagnosticity.

Example Matrix of Evidence and Arguments
Evidence/Argument Michael's employee Foreign Terrorist Serial Killer Domestic Terrorist
1. Conforms to the geospatial model of a serial criminal I C I C
2. All DC-area kilings occured within 30 days I CC C CC
3. The majority of the shootings were at or near shopping centers I CC CC CC
4. Shootings were all on major highways or interstates I II CC CC
5. There was only one shooting per location and often occured at gas stations I II C I
6. Sighting of a blue car with two black men I C C C
7. Sighting of a white van with two individuals at one killing I C C CC
8. Noise heard but shooter never seen I I CC C

Examine each the hypothesis one at a time by looking down the column to consider each hypothesis as a whole. Draw tentative conclusions by trying to disprove the hypotheses. Look at the “I”s to indicate evidence that may be inconsistent with a hypothesis. Generally, the hypothesis with the fewest “I”s is probably the most likely one. The hypothesis with the most “I”s is probably the least likely one.

Example Matrix of Evidence and Arguments
Evidence/Argument Michael's employee Foreign Terrorist Serial Killer Domestic Terrorist
Summary I=8
C=0
I=5
C=7
I=-1
C=10
I=-1
C=11