4,454 research outputs found
Friendship networks and social status
In empirical studies of friendship networks participants are typically asked,
in interviews or questionnaires, to identify some or all of their close
friends, resulting in a directed network in which friendships can, and often
do, run in only one direction between a pair of individuals. Here we analyze a
large collection of such networks representing friendships among students at US
high and junior-high schools and show that the pattern of unreciprocated
friendships is far from random. In every network, without exception, we find
that there exists a ranking of participants, from low to high, such that almost
all unreciprocated friendships consist of a lower-ranked individual claiming
friendship with a higher-ranked one. We present a maximum-likelihood method for
deducing such rankings from observed network data and conjecture that the
rankings produced reflect a measure of social status. We note in particular
that reciprocated and unreciprocated friendships obey different statistics,
suggesting different formation processes, and that rankings are correlated with
other characteristics of the participants that are traditionally associated
with status, such as age and overall popularity as measured by total number of
friends.Comment: 7 pages, 6 figure
Optimal Detection Strategies for an Established Invasive Forest Pest
When it comes to invasive species management, economists have focused on the trade-off between prevention of potential invasions and management of established populations. The intermediate step-detection of established populations on the landscape so that management can commence-has only recently received attention in the economics literature. A recent paper (Mehta et al., 2007) explores how biological and economic parameters affect optimal detection spending, recognizing that greater expenditures on detection can lead to smaller and more manageable population sizes upon detection because populations are discovered early. We build upon this framework by considering the optimal spatial allocation of detection effort when it is impossible to stop the advance of the main front of an invasive species, yet it is beneficial to detect and control sub-populations of the species that erupt ahead of the front. Our approach recognizes that the duration of management of sub-populations is constrained by the amount of time remaining before the main front arrives. Locations close to the front have less time remaining than locations that are more distant. These differences imply different levels of potential benefit from early detection; in particular, shorter management horizons translate into lower benefits from intervention. The optimal intensity of detection effort varies over space along with this variation in the benefits from management.Resource /Energy Economics and Policy,
Modeling Recreational Amenities in an Urban Setting: Location, Congestion, and Substitution Effects
In this article, we introduce a recreational amenity—a greenbelt park—into a simple urban economic model. For multiple possible park placements, we solve for the associated equilibrium urban structure, including the equilibrium rent gradient, city boundary, total number of park visits, the overall utility level, and total vehicle miles traveled. We examine how these change with alternative park placement sites. We then show how two modifications of the basic model—allowing congestion at the site to affect site quality, and introducing the possibility of a substitute site at the city’s periphery—affect our conclusions about how greenbelt location influences urban structure.urban structure, greenbelt, congestion, Research and Development/Tech Change/Emerging Technologies,
THE EFFECTS OF MINIMUM SIZE LIMITS ON RECREATIONAL FISHING
Minimum size limits have become an increasingly popular management tool in recreational fisheries. This popularity stems from the potential of minimum size limits to accomplish the twin goals of limiting overfishing and improving fishing quality through increasing the average size of fish caught. The success of minimum size limits in achieving these objectives depends, in a complicated way, on both the behavior of anglers and the biological mechanisms that guide the growth of the fish population. This paper examines these relationships and also considers the welfare implications of size regulations.Resource /Energy Economics and Policy,
USING OPTIMAL CONTROL TO CHARACTERIZE THE ECONOMIC AND ECOLOGICAL IMPLICATIONS OF SPATIAL EXTERNALITIES
This study uses optimal control theory to examine the dynamic features of agricultural landscapes characterized by spatial externalites. A stylized system of agricultural production and groundwater flow is used to illustrate how spatial externalities affect land use decisions over time. Policy alternatives are also considered.Environmental Economics and Policy,
URBAN PLANNING AND THE LOCATION OF ENVIRONMENTAL AMENITIES
In this paper, we use a simple urban economic model to study how choosing park locations within a city might contribute towards urban planning goals. For multiple possible park placements, we solve for the associated equilibrium urban structure, including the equilibrium rent gradient, city boundary, total number of park visits, the overall utility level, and total vehicle miles traveled. We then examine how these change with alternative park placement sites. We find that, as a prescription for reducing urban sprawl, park provision has mixed results. When placed close to the central business district, the park can result in an increase in inner city housing density; such placement could help ameliorate problems of commuter traffic congestion related to urban sprawl. Parks placed further out toward the periphery, although consistent with improved accessibility and utility maximization, have the opposite effect pulling residents away from the central business district and thereby likely worsening the congestion problem related to commuter traffic.Community/Rural/Urban Development, Environmental Economics and Policy,
A SPATIAL ANALYSIS OF THE ECONOMIC AND ECOLOGICAL EFFICACY OF LAND RETIREMENT
Most land management policies, such as land retirement, have multiple objectives. This study uses a cellular automata simulation model to explore how various spatial characteristics of land parcels on a hypothetical landscape contribute to the efficacy of land retirement in the presence of multiple retirement objectives- hydrological improvement, habitat improvement, and cost. Statistical analysis of the simulation results is used to tie particular spatial characteristics back to achievement of the three distinct objectives. In order to combine the three objectives into a measure that allows decision-makers to rank the desirability of different retirement strategies, linear and nonlinear goal programming frameworks are introduced. These frameworks are explored to determine what each implies about the tradeoffs that must be made among objectives and among the spatial land parcel characteristics that contribute to those objectives.Land Economics/Use,
A MODEL OF MINIMUM SIZE LIMIT REGULATIONS
Minimum size limits have become an increasingly popular management tool in recreational fisheries. This popularity stems from the potential of minimum size limits to accomplish the twin goals of limiting overfishing and improving fishing quality through increasing the average size of fish caught. The success of minimum size limits in achieving these objectives depends in a complicated way on both the behavior of anglers and the biological mechanisms that guide the growth of the fish population. This paper examines these relationships and also considers the welfare implications of size regulations.Resource /Energy Economics and Policy,
REDUCING PHOSPHORUS POLLUTION IN THE MINNESOTA RIVER: HOW MUCH IS IT WORTH?
A mail survey was conducted in Minnesota in 1997 to estimate the value of reducing phosphorus levels in the Minnesota River by 40%. The general population survey of river basin residents was designed to gather information about respondents' use of the Minnesota River in addition to their valuation of a hypothetical water quality improvement program. An estimate of the value of a specific recreational site along the River, the Minnesota Valley National Wildlife Refuge, was also obtained. Three distinct models were estimated in this research. The first was a contingent valuation model estimating the willingness to pay (WTP) for water quality improvements in the Minnesota River using only stated preference data. There were two different payment vehicles used in this question, an increase in the state income tax and a water bill surcharge. Respondents' annual mean willingness to pay for a 40% reduction in phosphorus was estimated to be 19.64 annually. The second model utilized stated preference data from respondents along with responses about their actual visit behavior. A panel model was constructed using the responses to three separate questions concerning the value of a 40% reduction in phosphorus pollution and yielded an estimate of 28.71 per individual.Environmental Economics and Policy,
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