Mark W. Horner

Bio: Mark W. Horner is an academic researcher from Florida State University. The author has contributed to research in topics: Population & Poison control. The author has an hindex of 36, co-authored 115 publications receiving 3865 citations. Previous affiliations of Mark W. Horner include Ohio State University & Texas State University.

Spatial Dimensions of Urban Commuting: A Review of Major Issues and Their Implications for Future Geographic Research∗

Abstract: Modern urban transportation systems continuously challenge, and are challenged by, the changing nature of 21st-century travel demand. Today, congestion is the norm in cities of the United States, and researchers and practitioners are seeking solutions to these problems. Urban commuting is identified as contributing to the suboptimal performance of transportation systems. This paper offers a review and critique of recent research on urban commuting, emphasizing geographical dimensions of this topic. Three broad areas of research related to urban commuting are discussed. These include (1) urban sustainability, (2) land use, and (3) geographic information systems (GIS). Major themes are examined in an effort to elicit thought on future geographic research. At the conclusion of the paper, summary remarks are provided and avenues for research are outlined.

Excess Commuting and the Modifiable Areal Unit Problem

Abstract: Excess commuting has emerged during the past two decades as an important construct for evaluating the spatial relationships between employment and residential locations. During this time-period, there has been an on-going debate regarding how one should measure excess commuting in urban regions. This paper contributes to the debate by focusing on the spatial issues inherent in excess commuting evaluation. We demonstrate how scale and unit definition (the modifiable areal unit problem) are manifested in the assessment of excess commuting, both in theoretical and empirical terms. To this end, a geographical information systems-based analysis is presented which explores spatial sensitivities in the excess commuting measure. Our results show that aggregation and spatial unit definition may have profound impacts on the estimation of excess commuting. This work provides a formal resolution to much of the recent debate regarding estimates of excess commuting in urban regions.

Extensions to the Concept of Excess Commuting

Abstract: When people commute to work longer or farther than the actual spatial arrangement of homes and workplaces suggest they could be commuting, people are engaging in excess commuting. In the aggregate, excess commuting is the nonoptimal or surplus work travel occurring in cities because people do not minimize their journeys to work. In this paper an alternative view of excess commuting based on a theoretical maximum commute is presented. The calculation of a theoretical maximum commute allows for an analysis of the range between the theoretical minimum and maximum commutes, which marks an improvement over current approaches to the measure of excess commuting. Conceptually, this range is taken to be the commuting capacity of a city. To what extent commuting capacity is consumed in terms of current levels of commuting forms a primary question of the analysis. A model is formulated and applied to 1990 Census data for a sample of US cities. Numerical and visual results suggest variation in the amount of excess co...

Life Cycle and Environmental Factors in Selecting Residential and Job Locations

Abstract: Home and workplace location choices are closely related. The determinants of these choices operate differently based on an individual's life cycle, particularly with regard to the presence or absence of children. Individuals with children often place value on greenspace and recreational opportunities, while those without children often prefer smaller residential lots and locations with access to services. Existing studies have found that if residential location desires are satisfied, people are less likely to emphasize the importance of job location irrespective of their life stage. Taking a different approach, this study examines home-workplace decisions from a commuting standpoint. Commute durations and personal characteristics are used to analyse individual behavior. The contributions of this work include the finding that environmental characteristics and amenities may explain the connection between commuting behavior and residential location choices. Existing studies have not connected environmental c...

Understanding individual human mobility patterns

Abstract: The mapping of large-scale human movements is important for urban planning, traffic forecasting and epidemic prevention. Work in animals had suggested that their foraging might be explained in terms of a random walk, a mathematical rendition of a series of random steps, or a Levy flight, a random walk punctuated by occasional larger steps. The role of Levy statistics in animal behaviour is much debated — as explained in an accompanying News Feature — but the idea of extending it to human behaviour was boosted by a report in 2006 of Levy flight-like patterns in human movement tracked via dollar bills. A new human study, based on tracking the trajectory of 100,000 cell-phone users for six months, reveals behaviour close to a Levy pattern, but deviating from it as individual trajectories show a high degree of temporal and spatial regularity: work and other commitments mean we are not as free to roam as a foraging animal. But by correcting the data to accommodate individual variation, simple and predictable patterns in human travel begin to emerge. The cover photo (by Cesar Hidalgo) captures human mobility in New York's Grand Central Station. This study used a sample of 100,000 mobile phone users whose trajectory was tracked for six months to study human mobility patterns. Displacements across all users suggest behaviour close to the Levy-flight-like pattern observed previously based on the motion of marked dollar bills, but with a cutoff in the distribution. The origin of the Levy patterns observed in the aggregate data appears to be population heterogeneity and not Levy patterns at the level of the individual. Despite their importance for urban planning1, traffic forecasting2 and the spread of biological3,4,5 and mobile viruses6, our understanding of the basic laws governing human motion remains limited owing to the lack of tools to monitor the time-resolved location of individuals. Here we study the trajectory of 100,000 anonymized mobile phone users whose position is tracked for a six-month period. We find that, in contrast with the random trajectories predicted by the prevailing Levy flight and random walk models7, human trajectories show a high degree of temporal and spatial regularity, each individual being characterized by a time-independent characteristic travel distance and a significant probability to return to a few highly frequented locations. After correcting for differences in travel distances and the inherent anisotropy of each trajectory, the individual travel patterns collapse into a single spatial probability distribution, indicating that, despite the diversity of their travel history, humans follow simple reproducible patterns. This inherent similarity in travel patterns could impact all phenomena driven by human mobility, from epidemic prevention to emergency response, urban planning and agent-based modelling.

Regression Diagnostics: Identifying Influential Data and Sources of Collinearity

Abstract: 1. Introduction and Overview. 2. Detecting Influential Observations and Outliers. 3. Detecting and Assessing Collinearity. 4. Applications and Remedies. 5. Research Issues and Directions for Extensions. Bibliography. Author Index. Subject Index.

Role of WHO.

Abstract: OVERVIEW The GRA Marketing Internship Program is offered to students who are interested in gaining valuable work experience through efforts in marketing, membership, sales, and events. Interns work directly to assist the Director of Marketing and Communications on various tasks relating to upcoming GRA events. During this internship, students will work a minimum of 10 hours a week and a maximum of 20 hours a week. Students are encouraged to earn credit for their internship, however this is a paid internship. Students interested in obtaining credit for their internship must consult their academic advisor or the intern coordinator at their academic unit.