Graduation Year

2008

Document Type

Thesis

Degree

M.A.

Degree Granting Department

Geography

Major Professor

Jayajit Chakraborty, Ph.D.

Committee Member

Pratyusha Basu, Ph.D.

Committee Member

Steven Reader, Ph.D.

Keywords

GIS, Privacy, Geocoding, Reverse geocoding, Masking

Abstract

Certain types of spatial data maintained and distributed by counties at taxpayer expense can be used with powerful mapping and analysis software, called Geographic Information Systems (GIS), to compromise an indvidual's locational privacy. The kind of privacy at threat here is referred to as geoprivacy, which is concerned with the rights to prevent disclosure of the location of one's home, workplace, or daily activities. While the availability of accessible and accurate geospatial data has increased geoprivacy concerns in recent years, this threat remains virtually unknown to the general public.

Although previous research has explored various components of the geoprivacy debate, the fragmented and localized nature of this work does not adequately address the threat on a large scale or lend itself for use in multi-level policy discussions. This thesis fills the need for a comprehensive and systematic geoprivacy study by examining county data availability in the entire state of Florida.

Ultimately, the success of geoprivacy violation attempts is determined by the availability and quality of the data being used. In order to evaluate this threat,a statewide inventory of the data necessary for a reverse geocoding operation, defined here as geoprivacy data elements, was created. A specific county (Bay County) with complete data availability was then selected and its geoprivacy data elements, specifically street, parcel, and address point layers were evaluated for their reverse geocoding and subsequent identity disclosure success. These findings were then compared with the results of the statewide inventory to determine the level of exposure that the state's residents are subjected to, based on their county's data offerings.

The statewide data inventory indicated substantial variation in county availability, quality, and delivery methods of the desired geoprivacy data elements. The results of the reverse geocoding operation performed with Bay County's geoprivacy data elements revealed that both property parcels and address points in conjunction with ownership information have a high rate of identity disclosure success. Geocodable streets were found to have a low rate of identity disclosure success and their results were comparable to a non-county maintained street layer that was used for control purposes. Although the street layers had a low rate of identity disclosure success, they could be used to identify a narrow range of address possibilities and still pose a geoprivacy threat. Forty-two counties in which approximately 13 million people reside make parcel data with ownership information available for free or purchase. Given the high success rate of the parcel data to disclose individual identity, this research suggests that the majority of the state's residents are vulnerable to potential geoprivacy violations.

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