Concept: Geocoding Addresses: Using ArcView

Introduction

There are occasions when the location of items may want to be mapped and inspected visually. There are also occasions when one may want to conduct small area analyses on the City of Winnipeg, as in the WRHA report (Frohlich, Fransoo, & Roos, 2001 ). This requires that the location of various items can be identified at the postal code level. However, if all one has are addresses without postal codes, then the following steps can be taken to assign postal codes to these addresses.

The program ArcView is used to accomplish these goals. One can map the location of items in Winnipeg or Manitoba, and also use the program to assign postal codes to items that have been geocoded.

Procedure

The set of addresses to be geocoded should be in a tab-delimited text file with field headers. The name of the field should contain 'address', just to make things easier.



Organization	Organization Type	Organization_Address	Program_Name
Winnipeg Native Alliance	Non-profit	185 Young Street	Girls Group
Winnipeg Native Alliance	Non-profit	185 Young Street	Cooking Club
Winnipeg Native Alliance	Non-profit	185 Young Street	Activities at YM-YWCA
West Broadway Community Church	Non-profit	102-222 Furby Street	Family Drop-in
Art City	Non-profit	616 Broadway	Art Program
Contemporary Dancers	Non-profit	109 Pulford Street	Dance Instruction
Inner City Youth Alive Inc.	Non-profit	418 Aberdeen Avenue	Youth Clubs
Inner City Youth Alive Inc.	Non-profit	418 Aberdeen Avenue	Youth Drop-In Program
Inner City Youth Alive Inc.	Non-profit	418 Aberdeen Avenue	Winter Camp Trip
Inner City Youth Alive Inc.	Non-profit	418 Aberdeen Avenue	Energy Club Leadership Dev. Prog.
Winnipeg Boys & Girls Club	Non-profit	929 Main Street	PEP Program
Wolseley Family Place	Non-profit	691 Wolseley Avenue	Family Resource Centre


In ArcView :


• Open the file containing the addresses by clicking on the Tables icon and then pressing the New button.
  
• In the window that pops up, locate the file, and press OK . The table with the list of addresses should now appear.

ArcView can now be used to assign a geospatial location to the set of addresses, using Statistics Canada's Street Network File (MCHP programmers see Heather Prior to access this file).


• Under View, click on Add Theme and locate the file.
  
• After the SNF is added, under the View menu, select Geocode Addresses . The Address Style should be 'US Streets' (i.e. the street number is followed by a space and then the street name, as in the above table)
  
• Identify the table containing the addresses, and the field in which the addresses are located. There are several options at this point.
  
  
  • The Interactive Match option is preferable.
    
  • Then, press Start . ArcView will automatically assign locations to all addresses that are straightforward.
    
    Note:
    
    • Addresses for which there are a number of good candidate matches, or for which the street is misspelled or does not appear in the SNF will not be matched.
      
    • Addresses with room or apartment numbers prior to the street number, as in the entry for the West Broadway Community Church above, will also fail.
    
    
  • When ArcView has completed this process, press Done . Both the number of matches (i.e. addresses that have been successfully geocoded) and the number of 'No Matches' will be displayed.

You now have the option to do an 'Interactive Re-match'. There are two things that can be done at this step:

1) Change the preferences for the matching procedure.


• Press Preferences and adjust the following tolerances: Spelling Sensitivity , Minimum Match Score , and 'Minimum score to be considered a candidate' . Lowering these numbers will affect the matching process. The first might permit some misspelled street names to be found. The second might assign addresses that were not previously considered. The third will identify candidates that may not have been considered on the first round.
  
• Then press Start . ArcView will go through the No Matches again using the new settings.

2) If there are relatively few No Matches, this procedure will be the one to follow.


• Do not press Start, do not adjust Preferences. Each address will appear one at a time in the window with a list of candidates identified by ArcView below (there may be none!).
  
  • If the appropriate location is in the list, then highlight it and press Match . If the location is not in the list, press Edit/Standardize to change either the house number or street name, or street suffix (e.g., ST, AV, CR, etc.) to find a match.
    
    • E.g. Addresses on Portage will not be identified if the street suffix is AVE rather than AV. Changing this one field will allow the location to be identified.
    
    
  • If the right candidate appears, choose it.
    
    • If no candidates appear despite all your alterations, then press Next to skip the address and move on.
      
    • Press Done , when completed.
      
    • Press Done again to exit the geocoding application.

Click on 'Attributes of Geocd1.shp' , which will now appear in the View window. This will make the points for the newly geocoded addresses appear in the View.


• To save this (in order to print), under the File menu, choose 'Export' and JPEG or Windows Bitmap file type.
  
  • Choose a file name and specify the location for it to be saved.

For assigning Postal Codes:

A table called 'Attributes of Geocd1.shp' should now exist.


• Click on the window for this table to make it the active window in ArcView.
  
• Under the 'Theme' menu, choose Add XY .

The postal code file should now be added to the View.


• Under the View menu, click Add Theme and find the Statistics Canada Postal Code Conversion file (MCHP programmers - please see Charles to access this file). The following will appear: Winnipeg streets, a series of points representing the programs, and a series of points representing the postal codes.
  
  
• Under the View menu, click on Geoprocessing Wizard .
  
  • Choose the final option, Assign Data by Location and click on Next .
    
  • Under 'Select a Theme to Assign Data to', choose the file, 'Attributesof Geocd1.shp' and
    
  • Under 'Select a theme to assign data from', choose the postal code file .
    
  • Click Finish . When this is done, postal codes will have been added to the 'Attributes of Geocd1.shp' Table which also contains all the information in the original table or addresses.

To export this file:


• Click on the table
  
• Under the File menu, choose Export . Choose the File Type and Location, give it an appropriate name, and save the file.

Note :

For assigning the CA's and NRN's from the file with postal codes, HealthSys and SAS must be used. Place the file into an appropriate folder in HealthSys.


• Consult Neighbourhood Clusters (prior name Neighbourhood Resource Networks (NRN))' to execute this step.