We have read and analyzed the article entitled “Prevalence of marijuana use among university students in Bolivia, Colombia, Ecuador and Peru”. We propose some objective points which could enhance the internal validity of the study (i.e., we suggest to report participation proportions).

Diversos estudos compreendem a análise de variáveis definidas no intervalo (0, 1), como porcentagens ou proporções. Os modelos mais adequados são os de regressão baseados nas distribuições beta e simplex. Neste trabalho, apresentamos o modelo de regressão beta proposto por Ferrari & Cribari-Neto (2004) e desenvolvemos o modelo de regressão simplex. Definimos um resíduo para o modelo de regressão simplex, muito útil na análise de diagnóstico, a partir do trabalho de Espinheira, Ferrari & Cribari-Neto (2008). Apresentamos uma forma geral para algumas medidas de diagnóstico, que podem ser aplicadas para os dois modelos. Avaliamos os modelos de regressão beta e simplex por meio de duas aplicações a dados reais, utilizando essas medidas. / Many studies consider the analysis of variables restricted to the interval (0, 1), as percentages and proportions. The most recommended models are based upon the beta and simplex distributions. In this work, we present the beta regression model proposed by Ferrari and Cribari-Neto (2004) and develop the simplex regression model. We propose a residual for the simplex regression model, which is very useful for the diagnostic analysis, based upon the work of Espinheira et al. (2008). We generalize some diagnostic techniques that can be applied to both models. We evaluate the beta and simplex models by two applications to real data, using those techniques.

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In America, buildings are often constructed with the intent of being utile only 30-40 years. All over the world though, there are buildings that are hundreds of years old that are still very functional. Historically, architecture was a part of mathematics, and in many periods of the past, the two were indistinguishable. Architects were often required to be also mathematicians in ancient times. The idea of this thesis is to identify the relationship between mathematics and architecture and to reintroduce them in order to create a module for successful design . Presence of mathematical boundaries help to attain visual consistency by relating a small scale to a larger scale. Spaces which meet these criteria are subconsciously realized as sharing critical qualities with natural and biological forms. Accordingly, they are perceived as more comfortable psychologically. Scaling coherence is a common element of traditional and vernacular architectures, but is often extensively deficient from contemporary architecture. Architecture has used proportional systems to create, or limit, the forms in building since its inception. In almost every building tradition, there exists a system of mathematical relations which governs the relationships between elements of design. These are often quite simple: whole number ratios or easily constructed geometric shapes. Many types of revival architecture have been employed in recent years, therefore it would be critical to identify why they have achieved a resurgence in popularity. However, historical allusions are generally superficial. No authentic scale or systems are used and the formerly unique qualities are not explored spatially. The attraction to, and association with, forms possessing harmonic proportions is a mitigating factor in design that needs to be addressed. The natural beauty stemming from proportion, mathematics, and the proper relationship of elements to the whole is what renders a building aesthetically and experientially pleasing to a human. Post-Modern architecture is all but going in the opposite direction of achieving this goal. The idea that a building should scale down to dimensions humans can relate to and reveal its stature in the experiential qualities must be extracted from traditional architecture and employed in contemporary techniques.

Cette recherche a pour objectif l'étude du raisonnement proportionnel chez des élèves cris de 2e secondaire confrontés à des situations de proportionnalité. Notre recherche de type exploratoire livre d'abord, dans la problématique, un portrait de plusieurs aspects des mathématiques dans la culture crie et de l'enseignement de cette discipline à la Commission scolaire crie qui gère l'éducation pour la Première Nation crie, depuis sa fondation en 1978. Le cadre théorique, pour sa part, expose les principaux résultats de recherches en didactique des mathématiques portant sur le raisonnement proportionnel. L'expérimentation est effectuée auprès de 12 élèves de 2e secondaire d'une classe française de l'école Willie J. Happyjack Memorial School à Waswanipi, une des neuf communautés cries situées dans le Grand Nord québécois. Au cours de cette expérimentation, sont présentés 13 problèmes de proportionnalité à 5 équipes de 2 ou 3 élèves chacune. Trois variables didactiques ont été retenues pour l'élaboration de ces problèmes: le facteur de présentation (texte, tableau, dessin); le type de rapport entre les données (entier, fractionnaire) ainsi que le nombre de données différentes (4 ou 6 données). L'analyse des productions des élèves est conduite de manière à dégager, pour chacun des problèmes, les calculs numérique et relationnel engagés par chacune des équipes. Sur la base de l'analyse des productions verbales et écrites des élèves, des hypothèses sont formulées quant à l'influence des 3 variables didactiques contrôlées a priori, sur les stratégies déployées pour traiter des problèmes portant sur des thèmes proportionnels. Les résultats de cette étude confortent en grande partie les écrits recensés dans le cadre théorique. En effet, les résultats rendent compte de la variété des calculs relationnels ainsi que de la diversité des calculs numériques (additifs et multiplicatifs) mis en oeuvre par les élèves pour résoudre les problèmes soumis. De plus, ces résultats permettent de préciser les limites de notre recherche tout en élaborant des hypothèses de travail pour des études ultérieures. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Enseignement secondaire, Mathématique, Proportionnalité, Culture crie.

Participants are slower to identify the print colour of incongruent colour words (e.g., the word ORANGE printed in green) than of congruent colour words (e.g., ORANGE printed in orange). The difference in time between these two conditions is the Stroop effect. The item-specific proportion congruent (ISPC) effect is the observation that the Stroop effect is larger for words that are presented mostly in congruent colours (e.g., BLUE presented 75% of the time in blue), and smaller for words that are presented mostly in a given incongruent colour (e.g., YELLOW presented 75% of the time in orange). One account of the ISPC effect, the modulation hypothesis, is that participants use the distracting word to modulate attention to the word (i.e., participants allow the word to influence responding when it is presented mostly in its congruent colour). Another account, the contingency hypothesis, is that participants use the word to predict the response that they will need to make (e.g., if the word is YELLOW, then the response is probably orange). Reanalyses of data from Jacoby, Lindsay, and Hessels (2003) along with results from new experiments are inconsistent with the modulation hypothesis, but entirely consistent with the contingency hypothesis. A mechanistic account of how responses are predicted is generated from the contingency hypothesis.

Participants are slower to identify the print colour of incongruent colour words (e.g., the word ORANGE printed in green) than of congruent colour words (e.g., ORANGE printed in orange). The difference in time between these two conditions is the Stroop effect. The item-specific proportion congruent (ISPC) effect is the observation that the Stroop effect is larger for words that are presented mostly in congruent colours (e.g., BLUE presented 75% of the time in blue), and smaller for words that are presented mostly in a given incongruent colour (e.g., YELLOW presented 75% of the time in orange). One account of the ISPC effect, the modulation hypothesis, is that participants use the distracting word to modulate attention to the word (i.e., participants allow the word to influence responding when it is presented mostly in its congruent colour). Another account, the contingency hypothesis, is that participants use the word to predict the response that they will need to make (e.g., if the word is YELLOW, then the response is probably orange). Reanalyses of data from Jacoby, Lindsay, and Hessels (2003) along with results from new experiments are inconsistent with the modulation hypothesis, but entirely consistent with the contingency hypothesis. A mechanistic account of how responses are predicted is generated from the contingency hypothesis.

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The researcher used self-constructed problem-solving and problem-posing activity sheets to ask students to do solving and posing by themselves, then discuss together afterwards. When teaching was completed each time, the researcher asked students to write learning diaries. The researcher referred to the students¡¦ records on problem-solving and on problem-posing and analyzed the categories of students¡¦ work and the contents of posing problems that students created as well as problem-solving strategies. He also referred to students¡¦ learning diaries to investigate into students¡¦ reflections on their problem-posing, and to make a record of self reflections during his problem-posing activities implementation. The results of this research showed that most of the students given problems included sufficient data for problem solving. Students virtually were able to make feasible problems but only few students can change the structures of the original given problems. Most of these problems are ¡¥Exchange problem¡¦ which be solved correctly by themselves. Most students solved problems by using the strategy relating to Multiples. The most important factor for accuracy and solving strategy is number type on the proportion problems. Moreover, students expressed that they were able to acquire study methods and have great enjoyment from problem-posing. Also, the teacher found that during problem-posing, students will advance in thinking and creativity.

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