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Softcover reprint of the hardcover 1st edition 2004The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Spatial interaction (SI) is the process whereby entities at different points in physical space make contacts, demand/supply decisions or locational choices. The entities can be individuals or firms and the choices can include housing, jobs, production quantities, exports, imports, face-to-face contacts, schools, retail centres and activity centres. The first SI models can be grouped under the generic heading gravity models. Their main characteristic is that they model the behaviour of demand or supply segments, rather than that of individuals and firms. This article traces the development of these models from their inception in the early part of the twentieth century to the present. The key advances include the replacement of the gravity analogy by the more general concepts of entropy or information theory, a statistical framework commonly used in physics. With the arrival of the regional science paradigm over 50 years ago, a key challenge has been to broaden these models compared to those arising in spatial economics, thus arriving at a more inclusive probabilistic framework. These efforts are discussed here, as well as inclusion of geographical advances, embracing activities as generators of travel, time-geography, recognition of spatial interdependencies, and use of neuro-computing principles. Copyright Springer-Verlag Berlin/Heidelberg 2003Spatial interaction, gravity models, entropy, probabilistic, spatial structure, neural networks,

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. www.econstor.eu Terms of use: Documents in D I S C U S S I O N P A P E R S E R I E S ABSTRACTGetting Stuck in the Blues: Persistence of Mental Health Problems in Australia * Do episodes of mental health problems cause future mental health problems, and if yes, how strong are these dynamics? We quantify the degree of persistence in mental health problems using nationally-representative, longitudinal data from Australia and system GMM-IV and correlated random effects approaches are applied to separate true from spurious state dependence. Our results suggest only a moderate degree of persistence in mental health problems when assuming that persistence is constant across the mental health distribution once individual-specific heterogeneity is accounted for. However, individuals who fell once below a threshold that indicates an episode of depression are up to five times more likely to experience such a low score again a year later, indicating a strong element of state dependence in depression. Low income is a strong risk factor in state dependence for both men and women, which has important policy implications. NON-TECHNICAL SUMMARYMental health problems are widely recognised as the leading cause of social and economic dysfunctioning. About 10% of the population in the Western world are diagnosed with depression and anxiety, the two major mental health disorders. These disorders are characterised by excessive worrying and gloomy thoughts, they tend to start early in life, and symptoms persist usually over many decades. It is not difficult to see why individuals who suffer from such emotional preoccupations are less likely to invest in their education and health, less successful in the labour market, and accumulate exorbitant health care costs throughout their lives. What is less obvious is the question why symptoms of depression and anxiety are so chronic in nature. This study hypothesises that a first-time experience of an episode of depression or anxiety will alter an individual's way of thinking and behaviour which causes the individual to get trapped in a vicious cycle of continuously experiencing such symptoms in the future. If this is the case, then treating such first episode will be crucial in averting the excessive long-term economic and social costs associated with chronic mental health problems. Our study finds that experiencing an episode of depression or anxiety doubles the probability of experiencing such an episode again in the next year. Low ...

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