Trimmed bagging.

Bagging has been found to be successful in increasing the predictive performance of unstable classifiers. Bagging draws bootstrap samples from the training sample, applies the classifier to each bootstrap sample, and then averages overal lobtained classification rules. The idea of trimmed bagging is to exclude the bootstrapped classification rules that yield the highest error rates, as estimated by the out-of-bag error rate, and to aggregate over the remaining ones. In this note we explore the potential benefits of trimmed bagging. On the basis of numerical experiments, we conclude that trimmed bagging performs comparably to standard bagging when applied to unstable classifiers as decision trees, but yields better results when applied to more stable base classifiers, like support vector machines.Bagging;

Trimmed bagging.

Bagging has been found to be successful in increasing the predictive performance of unstable classifiers. Bagging draws bootstrap samples from the training sample, applies the classifier to each bootstrap sample, and then averages over all obtained classification rules. The idea of trimmed bagging is to exclude the bootstrapped classification rules that yield the highest error rates, as estimated by the out-of-bag error rate, and to aggregate over the remaining ones. In this note we explore the potential benefits of trimmed bagging. On the basis of numerical experiments, we conclude that trimmed bagging performs comparably to standard bagging when applied to unstable classifiers as decision trees, but yields better results when applied to more stable base classifiers, like support vector machines.

Dandelions

https://digitalcommons.library.umaine.edu/mmb-me/1042/thumbnail.jp

Sero-epidemiological evaluation of changes in Plasmodium falciparum and Plasmodium vivax transmission patterns over the rainy season in Cambodia

<p>Abstract</p> <p>Background</p> <p>In Cambodia, malaria transmission is low and most cases occur in forested areas. Sero-epidemiological techniques can be used to identify both areas of ongoing transmission and high-risk groups to be targeted by control interventions. This study utilizes repeated cross-sectional data to assess the risk of being malaria sero-positive at two consecutive time points during the rainy season and investigates who is most likely to sero-convert over the transmission season.</p> <p>Methods</p> <p>In 2005, two cross-sectional surveys, one in the middle and the other at the end of the malaria transmission season, were carried out in two ecologically distinct regions in Cambodia. Parasitological and serological data were collected in four districts. Antibodies to <it>Plasmodium falciparum </it>Glutamate Rich Protein (GLURP) and <it>Plasmodium vivax </it>Merozoite Surface Protein-1₁₉(MSP-1₁₉) were detected using Enzyme Linked Immunosorbent Assay (ELISA). The force of infection was estimated using a simple catalytic model fitted using maximum likelihood methods. Risks for sero-converting during the rainy season were analysed using the Classification and Regression Tree (CART) method.</p> <p>Results</p> <p>A total of 804 individuals participating in both surveys were analysed. The overall parasite prevalence was low (4.6% and 2.0% for <it>P. falciparum </it>and 7.9% and 6.0% for <it>P. vivax </it>in August and November respectively). <it>P. falciparum </it>force of infection was higher in the eastern region and increased between August and November, whilst <it>P. vivax </it>force of infection was higher in the western region and remained similar in both surveys. In the western region, malaria transmission changed very little across the season (for both species). CART analysis for <it>P. falciparum </it>in the east highlighted age, ethnicity, village of residence and forest work as important predictors for malaria exposure during the rainy season. Adults were more likely to increase their antibody responses to <it>P. falciparum </it>during the transmission season than children, whilst members of the Charay ethnic group demonstrated the largest increases.</p> <p>Discussion</p> <p>In areas of low transmission intensity, such as in Cambodia, the analysis of longitudinal serological data enables a sensitive evaluation of transmission dynamics. Consecutive serological surveys allow an insight into spatio-temporal patterns of malaria transmission. The use of CART enabled multiple interactions to be accounted for simultaneously and permitted risk factors for exposure to be clearly identified.</p

Trimmed Bagging

Bagging has been found to be successful in increasing the predictive performance of unstable classifiers. Bagging draws bootstrap samples from the training sample, applies the classifier to each bootstrap sample, and then averages over all obtained classification rules. The idea of trimmed bagging is to exclude the bootstrapped classification rules that yield the highest error rates, as estimated by the out-of-bag error rate, and to aggregate over the remaining ones. In this note we explore the potential benefits of trimmed bagging. On the basis of numerical experiments, we conclude that trimmed bagging performs comparably to standard bagging when applied to unstable classifiers as decision trees, but yields better results when applied to more stable base classifiers, like support vector machines

Comparing degrees of constructionalization. Reduplicative coordination constructions with an emphatic meaning in Dutch and French

Dutch and French share a construction in which an element X occurs in a reduplicative coordination pattern: [X maar dan ook X] (lit. 'X but then also X') in Dutch and [X mais alors X] (lit. 'X but then X') in French (for Dutch, see Hoeksema (2001) and Cappelle (2012)). In both languages, this pattern can be used to put emphasis on X: (1) wij hebben alles maar dan ook alles gedaan om die mensen goed te begeleiden (... ) (CGN, shortened) 'lit. We have done everything but then also everything to guide these people appropriately' (2) je ne comprends pas les Wallons mais alors pas-du-tout (Valibel, shortened) 'lit. I do not understand the Walloons but then really not' Since these patterns combine a fixed sequence (maar dan ook / mais alors) with a variable element X (a (universal) quantifier, a degree adverb, an adjective, etc.) and since their emphatic meaning is not (entirely) predictable from their components, they seem to act like constructional idioms in the Construction Grammar sense (Croft & Cruse 2004, Goldberg 2006, Hoffmann and Trousdale 2013). These constructions should then clearly be distinguished from other instances of the sequences maar dan ook and mais alors with a true compositional (contrastive + consequential) meaning ('but then (also)'): (3) Je kunt dan verbinden tegen lagere kosten maar dan ook lagere bandbreedte natuurlijk (COW) 'Then you can connect at lower costs, but then also (with) lower band width of course' (4) Pour éviter de souffrir, on ne doit pas aimer, mais alors on souffre de ne pas aimer (web) 'To avoid suffering, one should not love, but then one suffers from the lack of love' The parallel between the Dutch construction and its French counterpart, however, is not as perfect as it at first sight might seem to be. For instance, the [X mais alors X] construction cannot only be used to emphasize X, but can also focus on a specific subtype of X, as in (5). In this case, the sequence mais alors cannot be translated by Dutch maar dan ook, but corresponds to maar dan wel (lit. 'but then well'). (5) lui il a: édifié aussi une ville mais alors une ville d'acier (...) (Valibel) 'lit. he also built a city, but then a city of steel' Hence, the question rises if in French, and possibly also in Dutch, different (sub)constructions should be distinguished, each with specific semantic-pragmatic effects. This question should not only be addressed at the semantic, but also at the formal level. Our corpus study, mainly based on web corpora (COW) and the databases Valibel for spoken French and Corpus Gesproken Nederlands for spoken Dutch, indicates, for instance, that, compared to Dutch, the French [X mais alors X] sequence allows more categorial variation of X and presents more cases without literal reduplication (6), which may suggest a less advanced degree of constructionalization. (6) j'en avais vraiment rien à foutre des cheveux blancs de Marie- Antoinette... Mais alors … rien à taper (web) 'lit. I couldn’t care less about the white hair of Marie-Antoinette… But then couldn’t give a fig.’ In sum, the present paper describes in more detail the extent to which the [X maar dan ook X] and the [X mais alors X] patterns are comparable and how their synchronic (syntactic and semantic-pragmatic) properties allow us to compare their degree of constructionalization. References Cappelle, B. 2012. Alles- maar dan ook allesbehalve grammaticaal, of hele- maar dan ook helemaal niks mis mee? Over Taal 51:3. 66-67. Croft, W. & Cruse, D. A. 2004. Cognitive linguistics. Cambridge: Cambridge University Press. Goldberg, A. 2006. Constructions at Work: the nature of generalization in language. Oxford University Press. Hoeksema, J. 2001. X maar dan ook echt X! : een geval van emfatische reduplicerende nevenschikking. Tabu 31:3/4. 119-140. Hoffmann, T. and G. Trousdale (eds.). 2013. The Oxford Handbook of Construction Grammar. Oxford: Oxford University Press. Corpora CGN (Corpus Gesproken Nederlands): http://lands.let.kun.nl/cgn/ COW (Corpora from the Web): http://hpsg.fu-berlin.de/cow/colibri/ Valibel: http://www.uclouvain.be/valibel-corpus.htm

Dutch 'laat staan' and French 'encore moins': Constructional effects

Dutch laat staan and French encore moins: Constructional effects Marking the twenty-fifth anniversary of Fillmore, Kay and O’Connor’s (FKO, 1988) seminal paper on construction grammar, this paper explores various non-compositional effects of the commonest expressions corresponding to let alone in Dutch and French: laat staan (lit. ‘let stand’) and encore moins (lit. ‘still less’), respectively, the latter alternating with the expression encore plus (lit. ‘still more’) in affirmative contexts: (1) a. I can’t walk let alone run. → nl: laat staan; fr: encore moins b. I struggle to walk let alone run. → nl: laat staan; fr: encore plus Drawing extensively on data systematically gathered from corpora (CGN, DPC, GlossaNet, Linguee, Valibel), the web, and sound recordings, we show that these expressions exhibit language-specific idiosyncrasies and must be stored along with detailed knowledge about (i) the syntactic properties of their possible grammatical environments, (ii) the semantico-pragmatic (including information-structural) effects they trigger at clause level and (iii) the prosody of the constituent they occur in. Syntactically, laat staan is often followed by the complementizer dat (‘that’) in spoken Dutch, even when there is no subordinating conjunction in the first conjunct, which renders difficult its analysis (provided by FKO for let alone) as a kind of coordinating conjunction. We further found support for Verhagen and Foolen’s (2003) and Janssen and Van der Leek’s (2009) observation that the phrase/clause preceding laat staan need not be explicitly or even implicitly negative, a possibility which also exists for let alone. Regarding interpretation, we question FKO’s suggestion (1988: 519) that the context then should provide a proposition whose truth the speaker denies or whose level of informativeness the speaker disagrees with. Evidence for non-compositional semantics was also found for French (et) encore moins, specifically in cases where it is used after jamais (‘never’) and/or personne (‘nobody’) in the first conjunct: (2) Dans ma vie, je n’ai jamais attaqué personne, encore moins Pepe et encore moins hier (www) ‘I’ve never attacked anyone in my life, still less Grandpa, and still less yesterday’ Such logically incoherent but common examples can be understood as making use of a conventionalized rhetorical device expressing that a situation’s actualization is unimaginable, even in a counterfactual world. Moreover, encore moins may occur after a conjunct which contains a (merely) conceptually negative element, such as difficile ‘difficult’, rather than an explicit marker of negation: (3) Difficile à croire, encore moins à prouver! (www) (lit.) ‘Hard to believe, still less to prove!’ In such contexts, one would have reasonably expected encore plus. Apparently, encore moins gets extended by some language users as a negative polarity scalar operator, encroaching (à la Himmelmann 2004) on the usage domain of encore plus after syntactically positive but semantically negative contexts. We suggest this may partly be due to the higher relative frequency of encore moins compared to encore plus, as confirmed by their use as translation equivalents of let alone in Linguee (a 4:1 ratio). Prosodically, laat staan and (en)core moins have a L+H* contour and are expected to occur in distinct intonation patterns correlating with information structure. (500 words)   References Fillmore, Charles J., Paul Kay and Mary Catherine O’Connor. 1988. Regularity and idiomaticity in grammatical constructions: The case of let alone. Language 64, 501–538. Himmelmann, Nikolaus P. 2004. Lexicalization and grammaticalization: Opposite or orthogonal? In Walter Bisang, Nikolaus P. Himmelmann, Björn Wieme (eds.), What Makes Grammaticalization?: A Look From Its Fringes And Its Components, pp. 21–42. Berlin: Mouton de Gruyter. Janssen, Theo A.J.M. and Federike C. van der Leek. 2009. Laat staan in de negatieve en de positieve zin. In: E. Beijk, L. Colman, M. Göbel, F. Heyvaart, T. Schoonheim, R. Tempelaars, V. Waszink (eds.) Fons verborum: feestbundel voor prof. dr. A.M.F.J. (Fons) Moerdijk aangeboden door vrienden en collega’s bij zijn afscheid van het Instituut voor Nederlandse Lexicologie, pp. 431–443. Leiden: Instituut voor Nederlandse Lexicologie. Verhagen, Arie and Ad Foolen. 2003. Hoe kan een woord zijn negatieve lading nou verliezen, laat staan integendeel? Over betekenisverandering bij ontkennende woorden. In: Jan Stroop (ed.) Waar gaat het Nederlands naartoe? Panorama van een taal, pp. 308¬–319. Amsterdam: Bert Bakker