scholarly journals Devil in the details: how can we avoid potential pitfalls of CATS regression when our data do not follow a Poisson distribution?

PeerJ ◽  
2022 ◽  
Vol 10 ◽  
pp. e12763
Author(s):  
Zoltán Botta-Dukát
Keyword(s):  
Poisson Distribution ◽  
Environmental Data ◽  
Parameter Estimates ◽  
Relative Role ◽  
Link Function ◽  
Original Algorithm ◽  
Regional Effects ◽  
Abundance Data ◽  
Relative Abundances

Background Community assembly by trait selection (CATS) allows for the detection of environmental filtering and estimation of the relative role of local and regional (meta-community-level) effects on community composition from trait and abundance data without using environmental data. It has been shown that Poisson regression of abundances against trait data results in the same parameter estimates. Abundance data do not necessarily follow a Poisson distribution, and in these cases, other generalized linear models should be fitted to obtain unbiased parameter estimates. Aims This paper discusses how the original algorithm for calculating the relative role of local and regional effects has to be modified if Poisson model is not appropriate. Results It can be shown that the use of the logarithm of regional relative abundances as an offset is appropriate only if a log-link function is applied. Otherwise, the link function should be applied to the product of local total abundance and regional relative abundances. Since this product may be outside the domain of the link function, the use of log-link is recommended, even if it is not the canonical link. An algorithm is also suggested for calculating the offset when data are zero-inflated. The relative role of local and regional effects is measured by Kullback-Leibler R2. The formula for this measure presented by Shipley (2014) is valid only if the abundances follow a Poisson distribution. Otherwise, slightly different formulas have to be applied. Beyond theoretical considerations, the proposed refinements are illustrated by numerical examples. CATS regression could be a useful tool for community ecologists, but it has to be slightly modified when abundance data do not follow a Poisson distribution. This paper gives detailed instructions on the necessary refinement.

Giscience in the Mountain Geography

2010 ◽  
Vol 27 (1-2) ◽  
pp. 81-90
Author(s):  
Krishna Poudel
Keyword(s):  
Spatial Data ◽  
Environmental Data ◽  
Temporal Data ◽  
Observation Systems ◽  
Research Findings ◽  
Temporal And Spatial ◽  
Temporal And Spatial Characteristics ◽  
Mountain Geography ◽  
Different Sources

Mountains have distinct geography and are dynamic in nature compared to the plains. 'Verticality' and 'variation' are two fundamental specificities of the mountain geography. They possess distinct temporal and spatial characteristics in a unique socio-cultural setting. There is an ever increasing need for spatial and temporal data for planning and management activities; and Geo Information (GI) Science (including Geographic Information and Earth Observation Systems). This is being recognized more and more as a common platform for integrating spatial data with social, economic and environmental data and information from different sources. This paper investigates the applicability and challenges of GISscience in the context of mountain geography with ample evidences and observations from the mountain specific publications, empirical research findings and reports. The contextual explanation of mountain geography, mountain specific problems, scientific concerns about the mountain geography, advances in GIScience, the role of GIScience for sustainable development, challenges on application of GIScience in the contexts of mountains are the points of discussion. Finally, conclusion has been made with some specific action oriented recommendations.

Enhancing Economic Growth and Government Revenue Generation in Nigeria: The Role of Diaspora Remittances

2021 ◽  
pp. 003464462110256
Author(s):  
Dal Didia ◽  
Suleiman Tahir
Keyword(s):  
Economic Growth ◽  
Parameter Estimates ◽  
Gross Domestic Product Growth ◽  
Correction Model ◽  
Vector Error Correction ◽  
Vector Error ◽  
Long Run ◽  
Short Run ◽  
The Empirical Analysis

Even though remittances constitute the second-largest source of foreign exchange for Nigeria, with a $24 billion inflow in 2018, its impact on economic growth remains unclear. This study, therefore, examined the short-run and long-run impact of remittances on the economic growth of Nigeria using the vector error correction model. Utilizing World Bank data covering 1990–2018, the empirical analysis revealed that remittances hurt economic growth in the short run while having no impact on economic growth in the long run. Our parameter estimates indicate that a 1% increase in remittances would result in a 0.9% decrease in the gross domestic product growth rate in the short run. One policy implication of this study is that Nigeria needs to devise policies and interventions that minimize the emigration of skilled professionals rather than depending on remittances that do not offset the losses to the economy due to brain drain.

scholarly journals The Role of Frost Processes in the Retreat of River Banks

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1812
Author(s):  
Karol Augustowski ◽  
Józef Kukulak
Keyword(s):  
Relative Role ◽  
Freezing And Thawing ◽  
Fine Grained ◽  
Fluvial Processes ◽  
Precise Calculation ◽  
Erosion Pins ◽  
Summer Half ◽  
Lateral Erosion ◽  
Summer Flood

The rate of bank retreat was measured using erosion pins on the alluvial banks of the rivers in the Podhale region (the boundary zone between Central and Outer Carpathians) during the hydrological year 2013/2014. During the winter half-year (November–April), the bank retreat was mainly caused by processes related to the freezing and thawing of the ground (swelling, creep, downfall). During the summer half-year (May–October), fluvial processes and mass movements such as lateral erosion, washing out, and sliding predominated. The share of fluvial processes in the total annual amount of bank retreat (71 cm on average) was 4 times greater than that of the frost phenomena. Erosion on bank surfaces by frost phenomena during the cold half-year was greatest (up to 38 cm) on the upper parts of banks composed of fine-grained alluvium, while fluvial erosion during the summer half-year (exceeding 80 cm) mostly affected the lower parts of the banks, composed of gravel. The precise calculation of the relative role of frost phenomena in the annual balance of bank erosion was precluded at some stations by the loss of erosion pins in the summer flood.

Grain Boundary Segregation in Titanium Dioxide: Evaluation of Relative Driving Forces for Segregation

2002 ◽  
Vol 751 ◽  
Author(s):  
Qinglei Wang ◽  
Guoda D. Lian ◽  
Elizabeth C. Dickey
Keyword(s):  
Titanium Dioxide ◽  
Driving Forces ◽  
Boundary Segregation ◽  
Solute Segregation ◽  
Dielectric Behavior ◽  
Relative Role ◽  
Transmission Electron ◽  
Fundamental Phenomenon ◽  
Versus Strain

ABSTRACTSolute segregation to grain boundaries is a fundamental phenomenon in polycrystalline metal-oxide electroceramics that has enormous implications for the macroscopic dielectric behavior of the materials. This paper presents a systematic study of solute segregation in a model dielectric, titanium dioxide. We investigate the relative role of the electrostatic versus strain energy driving forces for segregation by studying yttrium-doped specimens. Through analytical transmission electron microscopy studies, we quantitatively determine the segregation behavior of the material. The measured Gibbsian interfacial excesses are compared to thermodynamic predictions.

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