When Domains Collide (epan 2011)


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When Domains Collide (epan 2011)

  1. 1. When Domains Collide: Linking Databases to Determine Pupil Generation Rates Jessica Gormont , Jefferson County GIS/Addressing Office Tori Myers , Jefferson County Assessor’s Office Mark Schiavone , Jefferson County Department of Capital Planning and Management
  2. 2. School Impact Fee <ul><li>Fee levied against new residential construction </li></ul><ul><li>Calculated to ensure capacity expansion </li></ul>
  3. 3. School Impact Fee Impact Fee = ( Cost - Credit ) x Demand Generator Asset value per student Non-impact fee revenue per student Students per residential unit
  4. 4. Pupil Generation Rate: The number of school-aged children, usually expressed as level of schooling, per household. <ul><li>Traditionally Determined: </li></ul><ul><li>Using Census/PUMS data </li></ul><ul><li>Local census/sampling </li></ul>
  5. 5. Current Status: Jefferson County <ul><li>Pupil Generation data linked to Housing Unit Type: </li></ul><ul><ul><li>Single Family Detached (includes manufactured homes) </li></ul></ul><ul><ul><li>Townhome/Duplex </li></ul></ul><ul><ul><li>Multifamily Apartment </li></ul></ul>
  6. 6. Example: Miami-Dade County Pupil Generation Rates vs. Housing Unit Size (idealized)
  7. 7. Board of Education Transportation Database <ul><li>Highly granular: pupil generation per address </li></ul><ul><li>Lacks information about housing unit type or size </li></ul>
  8. 8. Assessor’s Database <ul><li>Highly granular: Housing unit type and size </li></ul><ul><li>Addresses not accurate – Parcel_ID highly accurate </li></ul>
  9. 9. How to Link? BOE data (good addresses) Assessor data (good map/parcel) County GIS Link addresses to addresses Link parcel_id to parcel_id
  10. 10. The Plan <ul><li>Analyze BOE data and clean </li></ul><ul><li>Pass BOE data to GIS for join </li></ul><ul><li>GIS pass data to Assessor to add building data </li></ul><ul><li>Deliver combined dataset to consultant for analysis </li></ul>
  11. 11. Preliminary Data <ul><li>Original parcel layer created in 2009 </li></ul><ul><li>IAS queries for tax code data </li></ul>
  12. 12. Finding Residential Addresses <ul><li>Spatial Join - address points & parcel polygons </li></ul><ul><ul><li>added Parcel ID to points </li></ul></ul><ul><li>Tabular Join - address points & IAS data </li></ul><ul><ul><li>added tax codes to address points </li></ul></ul>
  13. 13. Adding BOE Data <ul><li>Tabular Join - BOE data & address points </li></ul><ul><ul><li>Loss of 12.5% </li></ul></ul><ul><ul><li>Loss caused by variety of errors </li></ul></ul><ul><li>Secondary Visual Clean Up of BOE data </li></ul><ul><li>Second Tabular Join of BOE data </li></ul><ul><ul><li>loss of 10% - deemed acceptable </li></ul></ul>
  14. 14. Adding Additional Information <ul><li>Decided to add secondary information in case needed by contractor </li></ul><ul><li>Spatial Join to Jurisdiction layer </li></ul><ul><ul><li>Allowed for removal of address points within towns if necessary </li></ul></ul><ul><li>Spatial Join to Subdivision/MHP layer </li></ul><ul><ul><li>Allowed for separation of Mobile Homes in MHPs </li></ul></ul>
  15. 15. Final Data <ul><li>Data received from GIS </li></ul><ul><li>Several queries to retrieve data for Living unit size and number of bedrooms. </li></ul>
  16. 16. Final Data <ul><li>Final data sent to contractor contained: </li></ul><ul><ul><li>Physical Location Address </li></ul></ul><ul><ul><li>Parcel ID </li></ul></ul><ul><ul><li>Tax Code </li></ul></ul><ul><ul><li>Number of School Kids by Grade Level </li></ul></ul><ul><ul><li>Building Assessment Data </li></ul></ul><ul><ul><li>Jurisdiction </li></ul></ul><ul><ul><li>Subdivision/MHP name </li></ul></ul>
  17. 17. Results <ul><li>Original census data from 2000 </li></ul><ul><li>Only 3 housing unit types recognized </li></ul><ul><li>No further granularity </li></ul>
  18. 18. Results
  19. 19. Results
  20. 20. Results
  21. 21. Results
  22. 22. Conclusion <ul><li>Multiple databases linked with no loss of fidelity </li></ul><ul><li>GIS datasets are rich and merge well with other domains </li></ul><ul><li>Agencies able to create sophisticated studies at low cost </li></ul>