Paul Zandbergen | University of New Mexico (original) (raw)

Books by Paul Zandbergen

Python Scripting for ArcGIS is a guide to help experienced users of ArcGIS for Desktop get starte... more Python Scripting for ArcGIS is a guide to help experienced users of ArcGIS for Desktop get started with Python scripting. This book teaches how to write Python code that works with spatial data to automate geoprocessing tasks in ArcGIS. Readers can thus learn the skill set needed to create custom tools. The book contains 14 chapters, with the corresponding data and exercises on the accompanying DVD. A 180-day trial of ArcGIS 10.1 for Desktop software is also provided as an online download. Key topics in this book include: Python language fundamentals, Automating geoprocessing tasks, Exploring and manipulating spatial data, Working with geometries and rasters, Map scripting, Debugging and error handling, Creating functions and classes, and Creating and sharing script tools. More details on the book can be found at the Esri Press website: http://esriurl.com/5564. This includes sample chapters for download. Instructors who are considering the book as a textbook for a course can request a deskcopy from Esri Press: http://esripress.esri.com/offers/deskcopy.

Articles by Paul Zandbergen

Purpose -The purpose of this paper is to examine the influence of reference data, input address q... more Purpose -The purpose of this paper is to examine the influence of reference data, input address quality, and crime type on completeness and positional accuracy of street geocoded crime events. Design/methodology/approach -Existing data were analyzed using ArcGIS, including crime incident information, street network reference data, and address point and/or parcel reference data. Geocoding completeness was determined by the overall match rate. Positional accuracy was determined by comparing the Euclidian distance between street geocoded locations of crime events to the corresponding address point/parcel geocoded location. Findings -Results indicate that match rates vary by reference data, input address quality, and crime type. Local street centerline files consistently produced match rates that were as good as -and in many cases superior to -other types of reference data, including commercial data. Greater variability in positional accuracy was observed across reference data when crime type and input address quality was considered, but results were consistent with positional accuracy analysis conducted using data from other disciplines. Practical implications -Results provide researchers and practitioners with valuable guidance and insight into one of the most basic -albeit fundamental -procedures related to the spatio-temporal analysis of crime, suggesting that reference data required to produce geocoded crime incidents successfully and of high quality does not necessarily mean a large financial investment on the part of law enforcement agencies or researchers interested in the geospatial analysis of crime. Originality/value -Prior to this investigation, a comprehensive examination of the impact of data quality on geocoded crime events was absent from the literature.

Journal of Location Based Services, 2011

Metropolitan WiFi positioning is widely used to complement GPS on mobile devices. WiFi positionin... more Metropolitan WiFi positioning is widely used to complement GPS on mobile devices. WiFi positioning typically has very fast time-to-first-fix and can provide reliable location information when GPS signals are too weak for a position fix. Several commercial WiFi positioning systems have been developed in recent years and most newer model smart phones have the technology embedded. This study empirically determined the performance of WiFi positioning system on two different mobile devices. Skyhook's system, running on an iPhone and a laptop, was selected for this study. Field work was carried out in three cities at a total of 90 sites. The positional accuracy of WiFi positioning was found to be very similar on the two devices with no statistically significant difference between the two error distributions. This suggests that the replicability of WiFi positioning on different devices is high based on aggregate performance metrics. Median values for positional accuracy in the three study areas ranged from 43 to 92 m. These results are similar to earlier independent evaluations of Skyhook's system. The number of access points (APs) observed on the iPhone was consistently lower than that on the laptop. This lower number of APs, however, was not found to reduce positional accuracy. In general, no relationship was found between the number of APs and positional accuracy for either device, counter to earlier findings. The results indicate, however, that WiFi positioning can be achieved with a small number of APs (5–10), but that increased numbers of APs do not contribute to improved positional accuracy. Despite the agreement in aggregate performance metrics between the two devices, the replicability of WiFi positioning using Skyhook's system in terms of getting the same location by using two different devices at approximately the same place and time was relatively poor. Implications for location-based services on mobile devices are discussed.

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Mismatching sets of boundaries present a persistent problem in spatial analysis for many differen... more Mismatching sets of boundaries present a persistent problem in spatial analysis for many different applications. Dasymetric mapping techniques can be employed to estimate population characteristics of small areas that do not correspond to census enumeration boundaries. Several types of ancillary data have been used in dasymetric mapping but performance is often limited by their relatively coarse resolution and moderate correspondence to actual population counts. The current research examines the performance of using high resolution ancillary data in the form of individual address point datasets which represent the locations of all addressable units within a jurisdiction. The performance of address points was compared with several other techniques, including areal weighting, land cover, imperviousness, road density and nighttime lights. Datasets from 16 counties in Ohio were used in the analysis, reflecting a range of different population densities. For each technique the ancillary data sources were employed to estimate census block group population counts using census tracts as source zones, and the results were compared with the known block group population counts. Results indicate that address points perform significantly better compared with other types of ancillary data. The overall error for all block groups (n = 683) using address points is 4.9% compared with 10.8% for imperviousness, 11.6% for land cover, 13.3% for road density, 18.6% for nighttime lights and 21.2% for areal weighting. Using only residential address points rather than all types of locations further reduces this error to 4.2%. Analysis of the spatial patterns in the relative performance of the various techniques revealed that address points perform particularly well in low density rural areas, which typically present challenges for traditional dasymetric mapping techniques using land cover datasets. These results provide very strong support for the use of address points for small area population estimates. Current developments in the growing availability of address point datasets and the implications for spatial demographic analyses are discussed.

Computers & Geosciences, 2011

Global Positioning System devices are increasingly being used for data collection in many fields.... more Global Positioning System devices are increasingly being used for data collection in many fields. Consumer-grade GPS units without differential correction have a published horizontal positional accuracy of approximately 10–15 m (average positional accuracy). An attractive option for differential correction for these GPS units is the Wide Area Augmentation System (WAAS). Most consumer-grade GPS units on the market are WAAS capable. According to the Federal Aviation Authority (FAA), the WAAS broadcast message provides integrity information about the GPS signal as well as accuracy improvements, which are reported to improve accuracy to 3–5 m. Limited empirical evidence has been published on the accuracy of WAAS-enabled GPS compared to autonomous GPS. An empirical study was conducted comparing the horizontal and vertical accuracy of WAAS-corrected GPS and autonomous GPS under ideal conditions using consumer-grade receivers. Data were collected for 30-min time spans over accurately surveyed control points. Metrics of median, 68th and 95th percentile, Root Mean Squared Error (RMSE), and average positional accuracy in the horizontal and vertical dimensions were computed and statistically compared. No statistically significant difference was found between WAAS and autonomous position fixes when using two different consumer-grade units. When using WAAS, a third unit type exhibited a statistically significant improvement in positional accuracy. Analysis of data collected for a 27-h time span indicates that while WAAS is altering the estimated position of a point compared to an autonomous position estimate, WAAS augmentation actually appears to decrease the positional accuracy.

Utilizing both Assisted GPS (A-GPS) techniques and new high-sensitivity embedded GPS hardware, mo... more Utilizing both Assisted GPS (A-GPS) techniques and new high-sensitivity embedded GPS hardware, mobile phones are now able to achieve positioning in harsh environments such as urban canyons and indoor locations where older embedded GPS chips could not. This paper presents an empirical analysis of the positional accuracy of location data gathered using a high-sensitivity GPS-enabled mobile phone. The performance of the mobile phone is compared to that of regular recreational grade GPS receivers. Availability of valid GPS position fixes on the mobile phones tested was consistently close to 100% both outdoors and indoors. During static outdoor testing, positions provided by the mobile phones revealed a median horizontal error of between 5 . 0 and 8 . 5 m, substantially larger than those for regular autonomous GPS units by a factor of 2 to 3. Horizontal errors during static indoor testing were larger compared to outdoors, but the difference in accuracy between mobile phones and regular GPS receivers was reduced. Despite the modest performance of A-GPS on mobile phones, testing under various conditions revealed that very large errors are not very common. The maximum horizontal error during outdoor testing never exceeded 30 metres and during indoor testing never exceeded 100 metres. Combined with the relatively consistent availability of valid GPS position fixes under varying conditions, the current study has confirmed the reliability of A-GPS on mobiles phones as a source of location information for a range of different LBS applications.

Applied Geography, 2011

The Florida panther (Puma concolor coryi) is a relatively well studied species and it is well est... more The Florida panther (Puma concolor coryi) is a relatively well studied species and it is well established that the most important threat to panthers include limited habitat area and continued habitat loss and fragmentation. Despite the recognition that roads result in panther mortality and may limit panther movement there has been very limited research on the importance of roads. In the current study panther telemetry data from 1981 until 2004, detailed road networks and vegetation maps were used to determine vehicle-related mortality and road crossing behavior of the Florida panther. Differences by age and gender were determined, as well as the effect of road size. Results indicate that vehicle collisions are a major threat to the Florida panther population, especially adult males. Major roads present a stronger barrier to movement than minor roads, and the movement of females is more affected than that of males. Road networks in south Florida have essentially segregated the movement of the sexes and have fragmented the limited remaining habitat of the Florida panther.► Florida panther telemetry data from 1981 until 2004 as well as detailed road networks and vegetation maps were used to determine the influence of roads on individual panthers.► Vehicle collisions are a major threat to the Florida panther population, especially adult males.► Major roads form more of a barrier to movement than minor roads, and females are affected more than males.► Roads have essentially segregated the movement of the sexes and have fragmented not only the limited habitat of the Florida panther, but also segments of the adult population critical to the propagation of the species.

International Journal of Remote Sensing, 2011

Spatial data quality is a paramount concern in all geographical information systems (GIS) applica... more Spatial data quality is a paramount concern in all geographical information systems (GIS) applications. Existing standards and guidelines for spatial data commonly assume the positional error is normally distributed. While non-normal behaviour of the error in digital elevation data has been observed in previous research, current guidelines for digital elevation data still assume that the errors for observations in open terrain are normally distributed. This research employed an accuracy assessment dataset from a substantial lidar data collection effort, the North Carolina Floodplain Mapping Program. Strong evidence was found that the vertical error of lidar elevation data is not normally distributed and that both major and minor outliers are very common. Of the five land cover types considered, only the distribution for urban areas approximated a normal distribution, even though these observations were generally much less accurate than those for open terrain. No influence of slope on the occurrence of non-normal behaviour in the distributions was found. The RMSE z (root mean square error) statistic used to characterize the fundamental accuracy of digital elevation data was found to be very sensitive to the occurrence of outliers, questioning its use in current guidelines. *

Geocarto International, 2011

Repeatability of street geocoding was characterized in terms of completeness and positional accur... more Repeatability of street geocoding was characterized in terms of completeness and positional accuracy by using different street network datasets to geocode the same address input file. Match rates were highest for local street centrelines followed by StreetMap USA 2005 and TIGER 2000 data. Positional accuracy was highest for local street centrelines, while StreetMap USA 2005 and TIGER 2000 were nearly identical. Rural addresses were geocoded less accurately than urban addresses. Multi-family residential and commercial, institutional or industrial addresses were geocoded less accurately than urban single family residential addresses. The enhancement of TIGER 2000 data by commercial firms resulted in higher match rates but not in improved positional accuracy. The study has also highlighted the unique nature of multi-family and non-residential addresses in terms of the quality of their street geocoded locations. When such addresses are of specific interest alternatives to traditional street geocoding may need to be considered.

Cartography and Geographic Information Science, 2010

The purpose of this study is to determine the effect of vertical accuracy of a Digital Elevation ... more The purpose of this study is to determine the effect of vertical accuracy of a Digital Elevation Model (DEM) on the occurrence of topographic depressions. Stochastic depression modeling of a medium-resolution lidar DEM for a low-relief study area was carried out using Monte Carlo simulation of a range of Root Mean Square Error (RMSE) values for vertical error. Depth and size of observed depressions were compared to the stochastic modeling results in order to separate artificial from real depressions.

Criminal Justice and Behavior, 2010

Residential restrictions for sex offenders have become increasingly popular, despite the lack of ... more Residential restrictions for sex offenders have become increasingly popular, despite the lack of empirical data suggesting that offenders' proximity to schools or daycares contributes to recidivism. Using a matched sample of recidivists and nonrecidivists from Florida (n = 330) for the period from 2004 through 2006, the authors investigated whether sex offenders who lived closer to schools or daycares were more likely to reoffend sexually against children than those who lived farther away. No significant differences were found between the distances that recidivists and nonrecidivists lived from schools and daycares. There was no significant relationship between reoffending and proximity to schools or daycares. The results indicate that proximity to schools and daycares, with other risk factors being comparable, does not appear to contribute to sexual recidivism. These data do not support the widespread enactment of residential restrictions for sexual offenders.

Transactions in Gis, 2009

The 3G iPhone was the first consumer device to provide a seamless integration of three positionin... more The 3G iPhone was the first consumer device to provide a seamless integration of three positioning technologies: Assisted GPS (A-GPS), WiFi positioning and cellular network positioning. This study presents an evaluation of the accuracy of locations obtained using these three positioning modes on the 3G iPhone. A-GPS locations were validated using surveyed benchmarks and compared to a traditional low-cost GPS receiver running simultaneously. WiFi and cellular positions for indoor locations were validated using high resolution orthophotography. Results indicate that A-GPS locations obtained using the 3G iPhone are much less accurate than those from regular autonomous GPS units (average median error of 8 m for ten 20-minute field tests) but appear sufficient for most Location Based Services (LBS). WiFi locations using the 3G iPhone are much less accurate (median error of 74 m for 58 observations) and fail to meet the published accuracy specifications. Positional errors in WiFi also reveal erratic spatial patterns resulting from the design of the calibration effort underlying the WiFi positioning system. Cellular positioning using the 3G iPhone is the least accurate positioning method (median error of 600 m for 64 observations), consistent with previous studies. Pros and cons of the three positioning technologies are presented in terms of coverage, accuracy and reliability, followed by a discussion of the implications for LBS using the 3G iPhone and similar mobile devices.

International Journal of Industrial Organization, 2009

Theory predicts intense price competition results when firms cluster with rivals. Yet, strong evi... more Theory predicts intense price competition results when firms cluster with rivals. Yet, strong evidence of clustering is found in previous empirical research. Researchers typically measure clustering by comparing observed location patterns to random assignment. The random assignment benchmark does not, however, account for zoning and geography and therefore might overstate the extent of strategic agglomeration. As evidence, we find that public elementary schools cluster more than random, not because of agglomeration economies, but due to demand density and limited location options. We argue that a better measurement of strategic agglomeration is to compare across product markets with similar zoning and other location restrictions but different benefits from agglomeration. We use L-function analysis of five product markets in five cities. We find that retailers with greater ability to differentiate their products are more likely to strategically cluster.

Geography Compass, 2009

Many spatial analysis techniques rely on the ability to geocode individual locations based on add... more Many spatial analysis techniques rely on the ability to geocode individual locations based on addresses or other descriptive information. The quality of geocoding and its effect on spatial analysis have received some attention in the literature, in particular in the field of health. This article reviews the foundation of geocoding and presents a framework for evaluating geocoding quality. Errors introduced by street gecoding include incompleteness, positional error, and incorrect assignment to geographic units. A review of empirical studies suggests that these errors are neither small nor random in nature and that substantial bias may be introduced in spatial analysis that employs the results of geocoding. Several alternatives have also emerged, including the use of address points and parcels, and these are gradually becoming more widely used. Several areas for future research on geocoding have been identified: (i) refinements of address data models to incorporate complex addressing situations; (ii) development of error propagation techniques to determine the level of geocoding quality required for a particular analysis scenario; (iii) development of measures of reliability for geocoding results; (iv) comparative analysis of geocoding quality across different jurisdictions; and (v) validation of online geocoding services and volunteered geographic information.

Criminal Justice Policy Review, 2009

Geocoding is commonly employed to determine the location of addresses for use in spatial analysis... more Geocoding is commonly employed to determine the location of addresses for use in spatial analysis, including the establishment of residency restriction zones for sex offenders. Street geocoding has known limitations in terms of positional accuracy, which may adversely affect spatial analytic methods. A case study on sex offenders in Orange County, Florida, is used to characterize the positional accuracy of street geocoding and its impact on spatial analysis. Positional accuracy of street geocoded locations of sex offenders' residences, schools, and day care facilities was determined using Geographic Information Systems (GIS) by measuring the distance to the correct property boundaries. Results show that positional errors in street geocoding are substantial and may bias conclusions drawn from proximity analysis. Findings strongly suggest that street geocoding is not appropriate for assessing residency restriction violations for sex offenders. These findings have important implications for criminal justice policies related to residency restrictions for sex offenders.

Natural Hazards, 2009

Exposure of counties in the continental United States to tropical storm and hurricane conditions ... more Exposure of counties in the continental United States to tropical storm and hurricane conditions was determined using the historic record of storm tracks for the period 1851-2003. Two approaches were used to determine exposure: (1) cumulative number of hits, with a hit occurring when the storm's path crosses a county and (2) cumulative exposure factor, which describes how much of the county has been exposed to tropical storm, hurricane, and intense hurricane-force winds. In both approaches the top 10 counties in terms of cumulative exposure are in coastal Florida, North Carolina, and Louisiana. An explanatory model was developed to describe the patterns in the documented exposure, which included distance to coast, latitude, longitude, size, and shape of the counties. Multivariate linear regression confirmed that much of the spatial variability in exposure to storm conditions can be explained with these simple parameters.

Geography Compass, 2008

The Shuttle Radar Topography Mission (SRTM) was flown in February 2000 and collected the first ev... more The Shuttle Radar Topography Mission (SRTM) was flown in February 2000 and collected the first ever high-resolution near-global digital elevation data. The final SRTM data have become widely available at 1 arc-second resolution for the United States and 3 arc-second resolution for other areas. This article reviews the background of the SRTM mission, the data quality characteristics of the SRTM elevation data, and the many applications of SRTM elevation data that have emerged in recent years, including forest ecology, volcanology, glaciology, geomorphology, and hydrology. SRTM data have been particularly useful for areas where previously limited topographic data were available, but results from STRM data also compare reasonably well with those obtained from other high-resolution digital elevation models.

Computers, Environment and Urban Systems, 2008

The widespread availability of powerful geocoding tools in commercial GIS software and the intere... more The widespread availability of powerful geocoding tools in commercial GIS software and the interest in spatial analysis at the individual level have made address geocoding a widely employed technique in many different fields. The most commonly used approach to geocoding employs a street network data model, in which addresses are placed along a street segment based on a linear interpolation of the location of the street number within an address range. Several alternatives have emerged, including the use of address points and parcels, but these have not received widespread attention in the literature. This paper reviews the foundation of geocoding and presents a framework for evaluating geocoding quality based on completeness, positional accuracy and repeatability. Geocoding quality was compared using three address data models: address points, parcels and street networks. The empirical evaluation employed a variety of different address databases for three different Counties in Florida. Results indicate that address point geocoding produces geocoding match rates similar to those observed for street network geocoding. Parcel geocoding generally produces much lower match rates, in particular for commercial and multi-family residential addresses. Variability in geocoding match rates between address databases and between geographic areas is substantial, reinforcing the need to strengthen the development of standards for address reference data and improved address data entry validation procedures.

Journal of Location Based Services, 2011

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Computers & Geosciences, 2011

Applied Geography, 2011

International Journal of Remote Sensing, 2011

Geocarto International, 2011

Cartography and Geographic Information Science, 2010

Criminal Justice and Behavior, 2010

Transactions in Gis, 2009

International Journal of Industrial Organization, 2009

Geography Compass, 2009

Criminal Justice Policy Review, 2009

Natural Hazards, 2009

Geography Compass, 2008

Computers, Environment and Urban Systems, 2008

Transactions in Gis, 2008

Spatial data quality is a paramount concern in all GIS applications. Existing spatial data accura... more Spatial data quality is a paramount concern in all GIS applications. Existing spatial data accuracy standards, including the National Standard for Spatial Data Accuracy (NSSDA) used in the United States, commonly assume the positional error of spatial data is normally distributed. This research has characterized the distribution of the positional error in four types of spatial data: GPS locations, street geocoding, TIGER roads, and LIDAR elevation data. The positional error in GPS locations can be approximated with a Rayleigh distribution, the positional error in street geocoding and TIGER roads can be approximated with a log-normal distribution, and the positional error in LIDAR elevation data can be approximated with a normal distribution of the original vertical error values after removal of a small number of outliers. For all four data types considered, however, these solutions are only approximations, and some evidence of non-stationary behavior resulting in lack of normality was observed in all four datasets. Monte-Carlo simulation of the robustness of accuracy statistics revealed that the conventional 100% Root Mean Square Error (RMSE) statistic is not reliable for non-normal distributions. Some degree of data trimming is recommended through the use of 90% and 95% RMSE statistics. Percentiles, however, are not very robust as single positional accuracy statistics. The non-normal distribution of positional errors in spatial data has implications for spatial data accuracy standards and error propagation modeling. Specific recommendations are formulated for revisions of the NSSDA.

Environmental Health Perspectives, 2010

3. Joseph PM. Paradoxical ozone associations could be due to methyl nitrite from combustion of me... more 3. Joseph PM. Paradoxical ozone associations could be due to methyl nitrite from combustion of methyl ethers or esters in engine fuels. Environ Int 2007; 33: 1090–106. 4. Joseph PM. A novel hypothesis to explain trafficrelated nocturnal cough. Occup Environ Med 2008; 65: 575.

Criminal Justice and Behavior, 2008

The correspondence section is a public forum and, as such, is not peer-reviewed. EHP is not respo... more The correspondence section is a public forum and, as such, is not peer-reviewed. EHP is not responsible for the accuracy, currency, or reliability of personal opinion expressed herein; it is the sole responsibility of the authors. EHP neither endorses nor disputes their published commentary.

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P. Devereaux Jennings, Paul A. Zandbergen and Martin L. Martens scholarly strategy process resear... more P. Devereaux Jennings, Paul A. Zandbergen and Martin L. Martens scholarly strategy process research goes on, perhaps more than ever, suggesting that there is something fundamental and deeply interesting and profound about how strategies are made, where they originate, and how the process of strategy-making impacts the performance of organizations.(szulanski, Porac et al., 2005: xv)

Social and ecological systems must be more tightly coupled if the health of the biosphere is to b... more Social and ecological systems must be more tightly coupled if the health of the biosphere is to be improved. So goes the argument of several well-known ecological thinkers and activist organizations (Laszlo and others, 1977; Daly and Cobb, 1994; Gladwin, 1992; Meadows, 1992; Suzuki, 1997). Broadly speaking, this normative position also has theoretical and empirical support from organization theory, particularly from the institutional perspective (Friedland and Alford, 1991; Jepperson, 1991; Meyer and Scott, 1983).

The goal of this research program was to establish stronger quantitative relationships between hu... more The goal of this research program was to establish stronger quantitative relationships between human activities and practices in an urban watershed and the quality of the aquatic ecosystem so that proactive management programs could be developed to ameliorate the negative effects of the human activities.

EXECUTIVE SUMMARY The purpose of the current research was to contribute to the improved robustnes... more EXECUTIVE SUMMARY The purpose of the current research was to contribute to the improved robustness of predictive crime mapping techniques. Our goal was to investigate the effect of data quality on predictive hotspot mapping analysis in order to achieve the following three objectives:

• Development of an analysis methodology for housing affordability at the level of individual hou... more • Development of an analysis methodology for housing affordability at the level of individual housing units, calibrated using selected field observations for rental properties;• Application of the methodology to all of Miami-Dade County to generate statistical and cartographic summaries of the availability and spatial distribution of affordable housing in Miami-Dade County;

Institute for Resources and …, 2000

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Abstract: Training and education of all stakeholders involved in the process of watershed managem... more Abstract: Training and education of all stakeholders involved in the process of watershed management can contribute to it's effective implementation. Recent advances in distance education technologies have created new and promising opportunities for making training available to a wider audience.

Abstract—Error propagation modeling for terrain analysis can provide insights into the robustness... more Abstract—Error propagation modeling for terrain analysis can provide insights into the robustness of terrain derivatives. For unconstrained terrain derivatives, such as stream and watershed delineation, the most widely used technique for error propagation modeling employs a Monte Carlo simulation of a spatially autocorrelated error model.