Finding Hot Spots in ArcGIS Online: Minimizing the Subjectivity of Visual Analysis. Nicholas M. Giner Esri Parrish S.

Transcription

1 Finding Hot Spots in ArcGIS Online: Minimizing the Subjectivity of Visual Analysis Nicholas M. Giner Esri Parrish S. Henderson - FBI

2 Agenda The subjectivity of maps What is Hot Spot Analysis? What is Outlier Analysis? Complete Spatial Randomness Hot Spot Analysis Examples Pattern Analysis: ArcGIS Online vs. ArcGIS Pro Heat Maps vs. Hot Spot Maps How does Hot Spot Analysis work? How does Outlier Analysis work? Parrish Henderson Federal Bureau of Investigation

3 Maps are subjective Bronx, NY Water Quality Incidents January 2010 February 2017 Is there a spatial pattern in the location of these water quality incidents?

4 Maps are subjective Ft. Worth, TX Fire Response Times Is there a spatial pattern in the response times of these fire calls?

5 Maps are subjective Natural Breaks Southeast USA Economic Resilience to Natural Disasters (Counties) Equal Interval Quantile Geometric Interval Is there a spatial pattern in economic resilience to natural disasters in the Southeastern USA?

6 What is Hot Spot Analysis? Identifies statistically significant hot spots and cold spots (i.e. spatial clusters of high and low values) in geographic data

7 What is Outlier Analysis? Identifies statistically significant hot spots, cold spots and spatial outliers in geographic data

8 Complete Spatial Randomness (CSR) Hot Spot Analysis - Tests whether observed spatial clustering of high or low values is more pronounced than one would expect in a random distribution Outlier Analysis - Tests whether apparent similarity (spatial clustering of high or low values) or dissimilarity (spatial outliers) is more pronounced than one would expect in a random distribution

9 Examples of Hot Spot Analysis Point Locations Chicago Crimes: (2014) DC Snow Removal Complaints: Jan 2016 February 2016 NYC Graffiti: Jan Present

10 Examples of Hot Spot Analysis Point Attributes Austria Heavy Metals: Cadmium Concentration

11 Examples of Hot Spot Analysis Polygon Attributes Philadelphia Tracts: Market Potential for Medicaid DC Block Groups: Republican Party Affiliation

12 Pattern Analysis: ArcGIS Online vs. ArcGIS Pro ArcGIS Online ArcGIS Pro

13 Heat Maps vs. Hot Spot Maps

14 Demo #1 Heat Maps: Calculate Density in ArcGIS Online

15 How does Hot Spot Analysis work? Getis-Ord Gi* Statistic

16 How does Hot Spot Analysis work? Feature

17 How does Hot Spot Analysis work? Feature Neighborhood

18 How does Hot Spot Analysis work? Study Area Feature Neighborhood

19 How does Hot Spot Analysis work? Study Area Is this Neighborhood Significantly different from the study area?

20 How does Hot Spot Analysis work? Gi* statistic (calculated) Clustering of low values Clustering of high values

21 How does Hot Spot Analysis work? If significantly higher The feature is marked a Hot Spot Cold Spot 99% Confidence Cold Spot 95% Confidence Cold Spot 90% Confidence Not Significant Hot Spot 90% Confidence Hot Spot 95% Confidence Hot Spot 99% Confidence

22 How does Hot Spot Analysis work?

23 How does Hot Spot Analysis work?

24 How does Hot Spot Analysis work?

25 How does Hot Spot Analysis work?

26 How does Hot Spot Analysis work?

27 How does Hot Spot Analysis work? Cold Spot 99% Confidence Cold Spot 95% Confidence Cold Spot 90% Confidence Not Significant Hot Spot 90% Confidence Hot Spot 95% Confidence Hot Spot 99% Confidence

28 z-score (degree of clustering) How is Neighborhood defined? 6 5 Optimal neighborhood distance is where degree of clustering is highest 4 In ArcGIS Online, the optimal neighborhood can be chosen for you 3 Spatial Autocorrelation is calculated at multiple distances Distance

29 Demo #2 Hot Spots: Find Hot Spots in ArcGIS Online

30 How does Outlier Analysis work? Local Indicators of Spatial Association (LISA) Statistic

31 How does Outlier Analysis work?

32 How does Outlier Analysis work? Feature

33 How does Outlier Analysis work? Feature Neighborhood

34 How does Outlier Analysis work? Is this Neighborhood Is this Feature AND Significantly different from all other neighborhoods? Significantly different from all other features?

35 How does Outlier Analysis work? Moran s I statistic (calculated) Spatial outliers Clustering of similar values

36 How does Outlier Analysis work? Feature is higher than other features, Feature is higher than other features, Neighborhood is lower than other neighborhoods High Outlier HL HH Neighborhood is higher than other neighborhoods Feature is lower than other features, LL LH Feature is lower than other features, Neighborhood is lower than other neighborhoods Neighborhood is higher than other neighborhoods Low Outlier

37 How does Outlier Analysis work? High-High Cluster High-Low Outlier Low-High Outlier Low-Low Cluster Not Significant

38 Demo #3 Outliers: Find Outliers in ArcGIS Online

39 Analyzing Arrest Hot Spots in Baltimore Parrish Henderson Federal Bureau of Investigation

40 Print Your Certificate of Attendance Print stations located in the 140 Concourse Tuesday 12:30 pm 6:30 pm GIS Solutions Expo Hall B Wednesday 10:30 am 5:15 pm GIS Solutions Expo Hall B 5:00 pm 6:30 pm GIS Solutions Expo Social Hall B 6:30 pm 9:00 pm Networking Reception Smithsonian National Portrait Gallery

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