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Multiple-regression Analysis (multiple-regression + analysis)

Distribution by Scientific Domains

Earth and Environmental Science	33%

Selected Abstracts

Biotic and abiotic influences on the recruitment of male perch in Windermere, U.K.

JOURNAL OF FISH BIOLOGY, Issue 6 2004
C. G. M. Paxton
Perch Perca fluviatilis recruitment (based on the catch per unit effort, CPUE, of 2 or 3 year male perch) varied greatly from 1941 to 1995 in Windermere, U.K., with year class strengths strongly synchronous between the two basins of this temperate, mesotrophic lake. Statistically significant modified Ricker (Saila-Lorda) stock-recruitment curves could be fitted to data from three of four sampling sites, while the presence of widespread disease and late summer water temperature were also important explanatory variables. Multiple-regression analyses revealed no influences of pike Esox lucius recruitment, zooplankton abundance, or the climatic influences (i.e. North Atlantic Oscillation and displacement of the summer position of the Gulf Stream) on perch recruitment over and above associated influences from temperature. Fitted models realistically explained up to c. 60% of the observed variation in perch recruitment. [source]

Evidence that viral abundance across oceans and lakes is driven by different biological factors

FRESHWATER BIOLOGY, Issue 6 2008
JESSICA L. CLASEN
Summary 1. Samples from 16 lakes in central (n = 145) and western (n = 12) North America, the coastal northeast Pacific (n = 302) and the western Canadian Arctic Oceans (n = 142) were collected and analysed for viral, bacterial and cyanobacterial abundances and chlorophyll- a concentration. 2. Viral abundance was significantly different among the environments. It was highest in the coastal Pacific Ocean and lowest in the coastal Arctic Ocean. The abundances of bacteria and cyanobacteria as well as chlorophyll- a concentrations also differed significantly among the environments, with both bacterial abundance and chlorophyll- a concentration highest in lakes. As a consequence, the association of these variables with viral abundance varied among the environments. 3. Discriminant analyses with the abundance data indicated that the marine and freshwater environments were predictably different from each other. Multiple-regression analysis included bacterial and cyanobacterial abundances, and chlorophyll- a concentration as significant variables in explaining viral abundance in lakes. In regression models for the coastal Pacific Ocean, bacterial and cyanobacterial abundances were significant variables, and for the coastal Arctic Ocean viral abundance was predicted by bacterial abundance and chlorophyll- a concentration. 4. The relationship of viral and bacterial abundance differed between the investigated freshwater and marine environments, probably because of differences in viral production and loss rates. However, freshwaters had fewer viruses compared to bacteria, despite previously documented higher burst sizes and frequencies of infected cells, suggesting that loss rates may be more important in lakes. 5. Together, these findings suggest that there are different drivers of viral abundance in different aquatic environments, including lakes and oceans. [source]

Soil organic matter composition and soil lightness

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2004
Sandra Spielvogel
Abstract Relationships between soil lightness, soil organic matter (SOM) composition, content of organic C, CaCO3, and texture were studied using 42 top-soil horizons from different soil types located in southern Germany. SOM composition was determined by CPMAS 13C NMR spectroscopy, soil color was measured by diffuse-reflectance spectrophotometry and given in the CIE L*a*b* color coordination system (Commission Internationale de l'Eclairage, 1978). Multiple-regression analysis showed, that soil lightness of top-soil horizons is principally determined by OC concentration, but CaCO3 and soil texture are also major variables. Soil lightness decreased with increasing OC content. Carbonate content had an important effect on soil lightness even at low concentrations due to its lightening property. Regressions between soil lightness and organic C content were strongly linear, when the soils were differentiated according to texture and CaCO3 content. The aryl-C content was the only SOM component which correlated significantly with soil lightness (rS = ,0.87). In the linear regressions carried out on the different soil groups, soil aryl-C content was a more significant predictor for soil lightness than total OC content. Zusammensetzung der organischen Bodensubstanz und Bodenhelligkeit Der Zusammenhang zwischen Bodenhelligkeit, Zusammensetzung der organischen Substanz und Gehalt an Corg., CaCO3 und Textur wurde in 42 Oberböden aus verschiedenen Bodentypen Süddeutschlands untersucht. Die Zusammensetzung der organischen Substanz wurde mittels CPMAS- 13C-NMR-Spektroskopie bestimmt, die Bodenfarbe mittels Spektralphotometer und als Bodenhelligkeitswert im CIE L*a*b*-Farbkoordinatensystem (Commission Internationale de l'Eclairage, 1978) angegeben. Die Auswertung über multiple Regression zeigte, dass die Bodenhelligkeit hauptsächlich vom OC-Gehalt bestimmt wird; CaCO3 -Gehalt und Textur erwiesen sich als weitere relevante Variablen. Die Bodenhelligkeit nimmt mit zunehmendem OC-Gehalt ab. Aufgrund seiner stark aufhellenden Wirkung hat der Carbonatgehalt auch bei niedrigen Konzentrationen einen deutlichen Einfluss auf die Bodenhelligkeit. Bei Berücksichtigung der Textur und des Carbonatgehalts ergaben sich lineare Beziehungen zwischen Bodenhelligkeit und OC-Gehalt. Der Aryl-C-Gehalt des Bodens war als einzige Humuskomponente signifikant mit der Bodenhelligkeit korreliert (rS = ,0.87). Der Aryl-C-Gehalt des Bodens bestimmt die Bodenhelligkeit schärfer als der OC-Gehalt. [source]

Validity of the MMPI-2 basic and Harris,Lingoes subscales in a forensic sample

JOURNAL OF CLINICAL PSYCHOLOGY, Issue 12 2001
Timothy M. Osberg
The present study explored the MMPI-2 correlates of criminal history in a sample of prison inmates. Although Ma was the only basic scale to demonstrate a significant positive association to crime history, three Harris,Lingoes subscales also bore significant associations to this criterion. The Ma1 (amorality), Pd2 (authority problems), and Pd5 (self-alienation) subscales demonstrated positive associations with crime history. Hierarchical multiple-regression analyses were used to examine the incremental validity of the D, Pd, and Ma Harris,Lingoes subscales when added to their parent scales in the prediction of crime history. Only the Pd Harris,Lingoes subscales demonstrated incremental validity in the prediction of this criterion. The value of including the Ma and Pd Harris,Lingoes subscales in criminal risk assessment is discussed. © 2001 John Wiley & Sons, Inc. J Clin Psychol 57: 1369,1380, 2001. [source]

Explaining the "Natural Order of L2 Morpheme Acquisition" in English: A Meta-analysis of Multiple Determinants

LANGUAGE LEARNING, Issue S1 2005
Jennifer M. Goldschneider
This meta-analysis pools data from 25 years of research on the order of acquisition of English grammatical morphemes by students of English as a second language (ESL). Some researchers have posited a "natural" order of acquisition common to all ESL learners, but no single cause has been shown for this phenomenon. Our study investigated whether a combination of 5 determinants (perceptual salience, semantic complexity, morphophonological regularity, syntactic category, and frequency) accounts for the variance in acquisition order. Oral production data from 12 studies, together involving 924 participants, were pooled to obtain weighted accuracy scores for each of 6 grammatical functors. Results of a multiple-regression analysis showed that a large portion of the total variance in acquisition order was explained by the combination of the 5 determinants. Several of these determinants, it was argued, can be seen as part of a broad conceptualization of salience. Since the article was originally published, a number of meta-analyses have appeared in the applied linguistics literature (e.g., Masgoret & Gardner, 2003; Norris & Ortega, 2000; Ortega, 2003), and a book on meta-analysis in applied linguistics research is forthcoming (Norris & Ortega, in press). Meanwhile, research on the acquisition of Hebrew as a second language has begun to provide cross-linguistic evidence for how different aspects of salience contribute to ease or difficulty of second language acquisition (DeKeyser, Alfi-Shabtay, Ravid, & Shi, 2005) and how salience interacts with age of learning (DeKeyser, Ravid, & Alfi-Shabtay, 2005). [source]

Blinded side-to-side comparison of topical corticosteroid and tacrolimus ointment in children with moderate to severe atopic dermatitis

CLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 2 2007
P. D. Arkwright
Summary There is little information on the relative efficacy of topical tacrolimus and corticosteroids in the treatment of atopic dermatitis (AD) in children. In a single-centre, prospective, observer-blinded, side-to-side comparative study (ISRCTN65507338), 96 children with moderately severe AD were enrolled. The study aimed to compare the relative effectiveness of the child's usual topical corticosteroid with 0.03% tacrolimus ointment applied for 1 week, and if there was no difference, 0.1% tacrolimus ointment applied for a further week. Topical tacrolimus was found to be more effective than topical corticosteroid in 72 of the 93 children (77%) who completed the study. Using multiple-regression analysis with age, gender, pretreatment surface area affected and pretreatment corticosteroid potency as covariants, the only factor that reduced the chance of observing a beneficial effect with tacrolimus was moderate or potent topical corticosteroid use (OR = 0.13; 95% CI 0.02,0.74). [source]