Coefficient shifts in geographical ecology: an empirical evaluation of spatial and non-spatial regression

Copyright © 2009 The Authors. Copyright © ECOGRAPHY 2009.A major focus of geographical ecology and macro ecology is to understand the causes of spatially structured ecological patterns. However, achieving this understanding can be complicated when using multiple regressions, because the relative importance of explanatory variables, as measured by regression coefficients, can shift depending on whether spatially explicit or non-spatial modelling is used. However, the extent to which coefficients may shift and why shifts occur are unclear. Here, we analyze the relationship between environmental predictors and the geographical distribution of species richness, body size, range size and abundance in 97 multi-factorial data sets. Our goal was to compare standardized partial regression coefficients of non-spatial ordinary least squares regressions (i.e. models fitted using ordinary least squares without taking autocorrelation into account; “OLS models” hereafter) and eight spatial methods to evaluate the frequency of coefficient shifts and identify characteristics of data that might predict when shifts are likely. We generated three metrics of coefficient shifts and eight characteristics of the data sets as predictors of shifts. Typical of ecological data, spatial autocorrelation in the residuals of OLS models was found in most data sets. The spatial models varied in the extent to which they minimized residual spatial autocorrelation. Patterns of coefficient shifts also varied among methods and datasets, although the magnitudes of shifts tended to be small in all cases. We were unable to identify strong predictors of shifts, including the levels of autocorrelation in either explanatory variables or model residuals. Thus, changes in coefficients between spatial and non-spatial methods depend on the method used and are largely idiosyncratic, making it difficult to predict when or why shifts occur. We conclude that the ecological importance of regression coefficients cannot be evaluated with confidence irrespective of whether spatially explicit modelling is used or not. Researchers may have little choice but to be more explicit about the uncertainty of models and more cautious in their interpretation

Variaciones espaciales de la Sierra de Cartagena (Sureste Ibérico): el análisis de gradientes y los problemas de escala / Dolores Ferrer Castán ; directores Miguel Angel Esteve Selva, Luis A. Ramírez Díaz.

Tesis-Universidad de Murcia.Consulte la tesis en: BCA. GENERAL. ARCHIVO UNIVERSITARIO. T.M.-1052

Pensar la inactualidad del pensamiento de Michel Foucault en contextos comparados. Reseña del libro Michel Foucault: neoliberalismo y biopolítica de Vanessa Lemm

Submitted by Franciele Moreira ([email protected]) on 2017-03-31T15:35:00Z No. of bitstreams: 2 Artigo - Bradford Alan Hawkins - 2007 (2).pdf: 259727 bytes, checksum: 65c85e52b93375eea2c2c6adb5e11805 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2017-04-04T12:34:55Z (GMT) No. of bitstreams: 2 Artigo - Bradford Alan Hawkins - 2007 (2).pdf: 259727 bytes, checksum: 65c85e52b93375eea2c2c6adb5e11805 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2017-04-04T12:36:08Z (GMT) No. of bitstreams: 2 Artigo - Bradford Alan Hawkins - 2007 (2).pdf: 259727 bytes, checksum: 65c85e52b93375eea2c2c6adb5e11805 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2017-04-04T12:36:21Z (GMT). No. of bitstreams: 2 Artigo - Bradford Alan Hawkins - 2007 (2).pdf: 259727 bytes, checksum: 65c85e52b93375eea2c2c6adb5e11805 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2007-08We compiled 46 broadscale data sets of species richness for a wide range of terrestrial plant, invertebrate, and ectothermic vertebrate groups in all parts of the world to test the ability of metabolic theory to account for observed diversity gradients. The theory makes two related predictions: (1) ln-transformed richness is linearly associated with a linear, inverse transformation of annual temperature, and (2) the slope of the relationship is near 0.65. Of the 46 data sets, 14 had no significant relationship; of the remaining 32, nine were linear, meeting prediction 1. Model I (ordinary least squares, OLS) and model II (reduced major axis, RMA) regressions then tested the linear slopes against prediction 2. In the 23 data sets having nonlinear relationships between richness and temperature, split-line regression divided the data into linear components, and regressions were done on each component to test prediction 2 for subsets of the data. Of the 46 data sets analyzed in their entirety using OLS regression, one was consistent with metabolic theory (meeting both predictions), and one was possibly consistent. Using RMA regression, no data sets were consistent. Of 67 analyses of prediction 2 using OLS regression on all linear data sets and subsets, two were consistent with the prediction, and four were possibly consistent. Using RMA regression, one was consistent (albeit weakly), and four were possibly consistent. We also found that the relationship between richness and temperature is both taxonomically and geographically conditional, and there is no evidence for a universal response of diversity to temperature. Meta-analyses confirmed significant heterogeneity in slopes among data sets, and the combined slopes across studies were significantly lower than the range of slopes predicted by metabolic theory based on both OLS and RMA regressions. We conclude that metabolic theory, as currently formulated, is a poor predictor of observed diversity gradients in most terrestrial systems

II jornadas de intercambio de prácticas educativas en las aulas especializadas

Las Aulas Especializadas han sido un recurso de calidad y ha presentado un avance notable en las condiciones de escolarización del alumnado con trastornos del espectro autista, con trastornos específico del lenguaje, con discapacidad motriz y con polidiscapacidad. La satisfacción de los padres y madres, del profesorado y los progresos del alumnado avalan el camino emprendido. Lo que en el año 2002 eran experiencias de innovación pedagógica son una realidad repartida por toda la geografía andaluza. Se ha avanzado mucho, pero se debe seguir haciéndolo, completando la red de aulas, consolidando una oferta especializada en todas las provincias y, sobre todo, elevando el nivel técnico de los profesionales mediante actividades de formación como estas II Jornadas de Intercambio de Prácticas Educativas. Con ellas se ha querido facilitar que los maestros y maestras de toda Andalucía compartan sus recurso, sus estrategias metodológicas y sus conocimientos para conseguir una escuela más eficiente, más justa y más solidaria.AndalucíaInstituto Psicopedagógico Dulce Nombre de María (Málaga); Calle Manuel de Palacio, 17; 29017 Málaga; +34902290499; [email protected]

Supplement 1. Summary regression statistics and sources for all data sets.

<h2>File List</h2><blockquote> <p><a href="supplement1.txt">supplement1.txt</a></p> </blockquote><h2>Description</h2><blockquote> <p>Raw sample sizes (<i>n</i>) and standard errors (SE), geographically effective degrees of freedom (v*), adjusted standard errors (SE*), and adjusted 95% CI of OLS and RMA slopes for all data sets. Also provided is the information from Tables 1 and 2 to facilitate evaluation of each case, and the sources of the richness data (see <a href="appendix-A.htm">Appendix A</a> for full references). Data with linear relationships between rescaled temperature and ln richness are listed first, followed by nonlinear data divided into values to the left of their breakpoints (Cool) and to the right of their breakpoints (Warm) (see Table 2). North American reptiles, listed last, could not be analyzed with either linear or split-line regression.</p> </blockquote

Appendix A. Methods for data sets not available in the literature.

Methods for data sets not available in the literature

Coefficient shifts in geographical ecology: an empirical evaluation of spatial and non-spatial regression

Copyright © 2009 The Authors. Copyright © ECOGRAPHY 2009.A major focus of geographical ecology and macro ecology is to understand the causes of spatially structured ecological patterns. However, achieving this understanding can be complicated when using multiple regressions, because the relative importance of explanatory variables, as measured by regression coefficients, can shift depending on whether spatially explicit or non-spatial modelling is used. However, the extent to which coefficients may shift and why shifts occur are unclear. Here, we analyze the relationship between environmental predictors and the geographical distribution of species richness, body size, range size and abundance in 97 multi-factorial data sets. Our goal was to compare standardized partial regression coefficients of non-spatial ordinary least squares regressions (i.e. models fitted using ordinary least squares without taking autocorrelation into account; “OLS models” hereafter) and eight spatial methods to evaluate the frequency of coefficient shifts and identify characteristics of data that might predict when shifts are likely. We generated three metrics of coefficient shifts and eight characteristics of the data sets as predictors of shifts. Typical of ecological data, spatial autocorrelation in the residuals of OLS models was found in most data sets. The spatial models varied in the extent to which they minimized residual spatial autocorrelation. Patterns of coefficient shifts also varied among methods and datasets, although the magnitudes of shifts tended to be small in all cases. We were unable to identify strong predictors of shifts, including the levels of autocorrelation in either explanatory variables or model residuals. Thus, changes in coefficients between spatial and non-spatial methods depend on the method used and are largely idiosyncratic, making it difficult to predict when or why shifts occur. We conclude that the ecological importance of regression coefficients cannot be evaluated with confidence irrespective of whether spatially explicit modelling is used or not. Researchers may have little choice but to be more explicit about the uncertainty of models and more cautious in their interpretation