GIS Lecture 7

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GIS Lecture 7 Geocoding
2
Outline

• Geocoding
• Linear Address Matching
• Problems and Solutions
• Street Map
• Polygon Address Matching
• Improving the Process
• Geomasking
• WEB Sites

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Geocoding
4
Geocoding

• Address Geocoding
• Process of creating geometric representations for
  locations (such as point features) from
  descriptions of locations (such as addresses)
• Displays tabular data containing addresses as
  points on a map
• Finds locations on a map easily

5
Geocoding Examples

• Local Technology Council maps technology
  businesses by streets to see technology rich
  areas in a city
• Emergency dispatch operators geocode an address
  to determine who should respond to an emergency
  call
• County health director maps personal care and
  nursing homes and compares them to elderly
  population by neighborhood
• Business maps store locations and compares to
  competitor locations
• Others?

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What do you geocode?

• Tabular data with zip codes, addresses or
  latitude and longitude
• Text
• Databases

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What do you geocode?

• to Geographic maps
• TIGER Streets
• ZIP Codes

8
Address Matching
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Address Matching

• Address matching is a process that compares two
  addresses to determine whether or not they are
  the same.
• Looks for certain standards and makes a decision
  about whether addresses match.
• Incorrect, incomplete, or ambiguous address
  information will reduce the matching confidence.

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TIGER Files

• Geographic elements used to address match
• Lines
• streets, railroads, rivers
• Areas
• zip codes, census blocks, tracts, MCD/CCDs,
  places, counties, etc.
• Points
• landmarks such as churchs, schools, and other
  cultural features represented in TIGER as points

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TIGER Street Example
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Linear (Street) Address Matching
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Linear Address Matching (Streets)

• Urban street maps
• four street address numbers ranging from low to
  high for each side of a street segment.
• Left_from Left_to Right_from
  Right_to Street_name Type
• 101 199 100
  198 OAK ST

100
198
Oak St.
199
101
(80.731, 40.025) (80.729,
40.025)
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Address Matching Major Steps
Store.dbf
1437
123 Oak St
A
402
333 Pine Av
A
855
18 Bay Dr
B
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Address Matching Major Steps
Attributes of Streets
Parity
Street_
Side
To
Street
From
Type
5950
98
Oak
R
E
2
St
L
O
5950
99
Oak
1
St
198
Oak
R
E
100
St
6011
L
O
199
Oak
101
St
6011
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Address Matching Major Steps
Oak St
198
100
5950
6011
101
199
123
Pine Av
Attributes of Streets
Parity
Street_
Side
To
Street
From
Type
5950
98
Oak
R
E
2
St
L
O
5950
99
Oak
1
St
198
Oak
R
E
100
St
6011
L
O
199
Oak
101
St
6011
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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Direction, suffix 123 Oak ST W, Apt. 2,
  Pittsburgh, PA 15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Direction, suffix 123 Oak ST W, Apt. 2,
  Pittsburgh, PA 15213
• Direction, prefix 123 W Oak ST, Apt. 2,
  Pittsburgh, PA 15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Direction, suffix 123 Oak ST W, Apt. 2,
  Pittsburgh, PA 15213
• Direction, prefix 123 W Oak ST, Apt. 2,
  Pittsburgh, PA 15213
• Unit Number 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Direction, suffix 123 Oak ST W, Apt. 2,
  Pittsburgh, PA 15213
• Direction, prefix 123 W Oak ST, Apt. 2,
  Pittsburgh, PA 15213
• Unit Number 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Zone, city 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Zone, zip code 123 Oak ST W, Apt. 2, Pittsburgh,
  PA 15213

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Address Components

• Number 123 Oak ST W, Apt. 2, Pittsburgh, PA 15213
• Street Name 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Street Type 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Direction, suffix 123 Oak ST W, Apt. 2,
  Pittsburgh, PA 15213
• Direction, prefix 123 W Oak ST, Apt. 2,
  Pittsburgh, PA 15213
• Unit Number 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Zone, city 123 Oak ST W, Apt. 2, Pittsburgh, PA
  15213
• Zone, zip code 123 Oak ST W, Apt. 2, Pittsburgh,
  PA 15213
• Items for Single Number Street Address
• Address Unit
  City Zip Code
• 123 Oak ST W Apt. 2
  Pittsburgh 15213

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Street Address Matching Problems and Solutions
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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run
• Place Names
• CMU, PNC Park, Station Square

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run
• Place Names
• CMU, PNC Park, Station Square
• Intersections
• 5th AV and Craig ST

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run
• Place Names
• CMU, PNC Park, Station Square
• Intersections
• 5th AV and Craig ST
• Zones
• 100 Main ST 15101, 100 Main ST 16202

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run
• Place Names
• CMU, PNC Park, Station Square
• Intersections
• 5th AV and Craig ST
• Zones
• 100 Main ST 15101, 100 Main ST 16202
• Post Office Boxes
• P.O. Box 125

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Possible Problems

• Variations in Street Names
• Fifth Avenue, Fifth Ave., 5th AV
• Saw Mill Run, Route 51
• Data Entry Errors
• Fidth Avenue
• Sawmill Run
• Place Names
• CMU, PNC Park, Station Square
• Intersections
• 5th AV and Craig ST
• Zones
• 100 Main ST 15101, 100 Main ST 16202
• Post Office Boxes
• P.O. Box 125
• Missing Street (TIGER) information

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Solution Correct Intersections

• Format
• Forbes AV Craig ST
• Grant ST 5th AV
• Default Delimiters
• ArcView
• ARC/INFO /

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Solution Use Standard Directions

• E E
• EA E
• EAS E
• EAST E
• EX EX
• EXT EX
• EXTENDED EX
• EXTENSION EX
• N N
• NO N
• NORTE N
• NORTH N
• NE NE
• NORTHEAST NE

• NW NW
• NORTHWEST NW
• S S
• SO S
• SOUTH S
• SE SE
• SOUTHEAST SE
• SW SW
• SOUTHWEST SW
• W W
• WE W
• WEST W

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Solution Use Standard Street Type Abbreviations

• CR CR
• Crescent CR
• CRSG CRSG
• CSWY CSWY
• DR DR
• Drive DR
• DRV DR
• EXP EXWY
• Expressway EXWY
• EXPWY EXWY
• Freeway FRWY
• FRWY FRWY

• FWY FRWY
• Highway HWY
• HWY HWY
• HY HWY
• LA LA
• Lane LA
• LN LA
• Loop Loop
• Motorway MTWY
• MTWY MTWY
• Parkway PKWY
• PKWY PKWY
• etc.

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Improving Address Matching

• Integrate User Data Entry and Address Matching
• Purchase or Build High Quality Maps (Field
  Verification)
• Correct and Maintain Maps (Lab)
• Assign House Numbers in Rural Areas

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SolutionAlias Table

• DBF Table (Name of Your Choice)
• Alias Address
• CMU 5000 Forbes Av
• Carnegie Mellon 5000 Forbes AV
• Carnegie Mellon Univ 5000 Forbes AV
• Carnegie Mellon University 5000 Forbes AV
• Etc.

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StreetMap USA
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Polygon Address Matching
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TIGER Files Polygon Topology

• Zip Code
• American Indian Reservation
• Alaska Nature Village Statistical Area
• Tribal Designated Statistical Area
• Tribal Jurisdiction Statistical Area
• Alaska Nature Regional Corp.
• FIPS State Code
• FIPS County Code
• MCD
• Place
• Census Tract/Block Numbering Area
• Tabulation Block

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TIGERPolygons - Zipcodes/Parcels

• Polygon features can be identified by their
  parcel numbers, postal zip, or zip4 codes
• Parcel_Number (1046)
• ZIP (15218)
• ZIP 4 (15218-1234)

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Polygon Address Matching (Zip Codes)
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Spatially Join to Make Choropleth Map
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Address Matching in ArcView
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Address Matching in ArcMap

• Create a new Address Locator in ArcCatalog

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Address Matching in ArcMap

• Decide what Locator style to use

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Address Matching in ArcMap

• Modify Address Locator properties

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Address Matching in ArcMap

• Add the tabular data in ArcMap

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Address Matching in ArcMap

• Add the Address Locator in ArcMap
• Add the streets or zipcode layers

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Address Matching in ArcMap

• Address match the tabular data to the map
• Rematch if necessary

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Geomasking
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Geomasking

• Why Geomasking?
• Confidentiality of a patients identity
• In the database latitude and longitude
• On a map specific point
• Two main purposes of geomasking
• Release of data for subsequent analysis
• Spatial patterns (e.g. obesity trends)
• Maps for public release

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Geomasking Methods

• Transformations
• Translation shift all points a fixed distance
  and direction
• Scale expand or contract all points by a scaling
  factor
• Rotation rotate all points a fixed angle
• Random pertubation
• Random distributions uniform or normal
• Aggregation

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How to Geomask

• Outside a GIS
• Can perform arithmetic on X and Y (latitude and
  longitude fields)
• Can set a minimum or maximum distance based on
  population density (urban vs rural)
• Inside a GIS
• Generate a random point within a circular buffer
• Add a population density layer to decide min/max
  distances
• Can avoid placing points out of bounds

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To Learn More

• http//gis.esri.com/library/userconf/health04/pape
  rs/pap3012.pdf
• http//www.spatialecology.com/htools/rndpnts.php

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Useful WEB Sites

• http//www.usps.gov/
• http//www.geocode.com/geocode.htm
• http//www.mapquest.com
• http//www.maps.google.com
• http//www.zipinfo.com
• http//geocoder.us
• http//www.batchgeocoder.com

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Summary

• Geocoding
• Linear Address Matching
• Problems and Solutions
• Street Map
• Polygon Address Matching
• Improving the Process
• Geomasking
• WEB Sites