Uma analise empírica do mercado de revenda de carros usando raspagem de dados da internet

Tese (doutorado)—Universidade de Brasília, Departamento de Economia, Brasília, 2016.Estudamos o mercado secundário de automóveis utilizando anúncios de venda de carros na internet. O mercado secundário de carros é importante por introduzir uma série de substitutos parciais para os carros novos. Apesar de sua relevância, existem relativamente poucos estudos sobre o mercado de carros usados. Contribuímos para a literatura ilustrando como as técnicas de Big Data podem contribuir para pesquisa econômica. Inspirados pelo paradigma do Big Data, nós construímos uma base de dados utilizando Python e Web Scraping. A segmentação de carros usados, utilizando um algoritmo não-supervisionado, revela clusters que possuem baixa correlação com os segmentos de carros zero quilômetro. Sabe-se que as montadoras projetam carros utilizando comunalidade para obter economias de custos. Usando modelos de comunalidade, preços hedônicos e modelos hierárquicos, verificamos que os efeitos da comunalidade sobrevivem no mercado secundário de carros. Por último, caracterizamos a perda de preço dos veículos utilizando modelos de crescimento exponencial, onde o ponto de inflexão determina o momento de desaceleração da curva de depreciação. Consumidores de carros zero irão absorver grande perda de preços no momento da revenda, enquanto consumidores de veículos com idade maior que o ponto de inflexão não terão grandes perdas de preço.We study the secondary car market using cars sales data in on-line advertisements. The secondary car market is important for introducing a lot of partial substitutes for new cars. But despite its importance, there are relatively few studies about the secondary car market. We contribute to the literature by illustrating how Big Data techniques can contribute to economic research. We inspired ourselves by the paradigm of Big Data and built a database using Python programming and Web Scraping and then we segment the used cars market using an unsupervised algorithm. This reveals clusters with low correlation with the new cars market segments. It is well known that, in order to achieve savings costs, the cars manufacturers uses commonality in production. We built over the literature on commonality models, hedonic price framework and hierarchical models to show that the effect of commonality still survives in the secondary cars market. Finally, we characterized the loss of cars prices using the exponential growth models, where the inflection point determines the time of deceleration in the depreciation path. We find that zero car buyers will absorb great loss in price at the time of resale, while used cars buyers of vehicles older than the inflection point will not have big losses in prices at the time of resale

Avaliação de Impacto de Programas de Incentivos Fiscais à Inovação - Um Estudo sobre os Efeitos do PDTI no Brasil

A prática de incentivos fiscais à inovação é comumente adotada por diversos países com objetivo de estimular as formas na realização de atividades tecnológicas, sendo especialmente dirigidos as atividades de Pesquisa e Desenvolvimento (P&D). O uso generalizado desses incentivos culminou em uma ampla discussão internacional questionando-se sua efetiva capacidade de estimular (ou não) as formas beneficiárias a ampliarem seus investimentos em atividades tecnológicas, e assim, acelerar o ritmo de inovação no país. Dentro dessa discussão, o presente trabalho tem como objetivo realizar um exercício empírico de avaliação de um programa brasileiro de incentivos fiscais às atividades tecnológicas, o Programa de Desenvolvimento Tecnológico Industrial (PDTI). Para capturar os efeitos desse programa no comportamento das forrmas beneficiarias em relação as não-beneciarias, quanto a decisão de gasto em atividades tecnológicas, será aplicado o método Propensity Score Matching entendido como uma técnica para determinação de quase-experimentos, baseada em algoritmos de pareamento de indivíduos pertencentes a grupos distintos, cujo objetivo é julgar os efeitos de um determinado tratamento.Incentivos Fiscais, Inovação, Propensity Score Matching

Impacts of the Brazilian science and technology sectoral funds on the industrial firms’ R&D inputs and outputs

Os fundos setoriais foram instituídos no final da década de 1990, com o propósito de criar condições mais estáveis de financiamento público às atividades de ciência, tecnologia e inovação (CT&I) no Brasil. De maneira análoga ao que se observa com outros instrumentos de incentivo à inovação nas empresas, a expectativa é que o acesso aos fundos setoriais contribuiria para o aumento dos esforços tecnológicos e para o alcance de melhores resultados pelas empresas. O objetivo deste trabalho é, portanto, avaliar o impacto desses fundos sobre os esforços tecnológicos e sobre os resultados das empresas industriais no Brasil, no período 2001 a 2006. A base teórica para a discussão é a literatura internacional que tem, recorrentemente, analisado o efeito crowding in ou crowding out de políticas de apoio à inovação nas empresas. Esses trabalhos buscam verificar se as políticas adotadas complementam os recursos alocados nas atividades de inovação pelas empresas ou se haveria simplesmente a substituição desses últimos por recursos públicos. Neste artigo, uma técnica quasi-experimental é aplicada para comparar as empresas que acessaram os fundos setoriais com aquelas que não os acessaram, usando dados de painel que incluem informações sobre esforços tecnológicos e resultados. O grupo de controle é definido com base no algoritmo de Propensity Score Matching (PSM), visando eliminar o viés de seleção no acesso aos fundos, o que faz com que, a priori, as empresas que acessam esses recursos trilhem uma trajetória distinta daquelas que não acessam. Estimativas das diferenças percentuais das taxas de crescimento dos esforços tecnológicos indicam significativo descolamento entre os grupos de tratamento e controle e permitem que se rejeite a hipótese de crowding out. Estima-se que o diferencial na taxa de crescimento do PoTec – que corresponde à proxy para os esforços tecnológicos – seja de 6,8 p.p. no primeiro ano, 11,5 p.p. no segundo, 15,7 p.p. no terceiro e 26,7 p.p. no quarto ano após o acesso. Os fundos setoriais apresentam ainda impacto positivo e significativo no pessoal ocupado total, embora apenas um impacto marginalmente significante nas exportações de alto conteúdo tecnológico tenha sido observado após quatro anos nas empresas que compõem o grupo de tratamento. Adicionalmente, uma análise preliminar dos impactos dos diferentes instrumentos que compõem os fundos setoriais permite associar a maior parte dos impactos dos recursos à concessão de crédito em condições mais favoráveis. _________________________________________________________________________________ ABSTRACTThe Brazilian science and technology sectoral funds were established at the end of the 1990s, aiming at providing more stable financial resources to science, technology, and innovation (ST&I) activities in the country. Similarly to other instruments used to foster innovation at the firm level, the sectoral funds are expected to increase firms’ technological efforts as well as their result indicators. The aim of this paper is to evaluate the impacts of these funds on the industrial firms’ R&D inputs and outputs in Brazil during the period between 2001 and 2006. Several papers have discussed the additionality or crowding out effects of innovation policies that involve grants and fiscal incentives, for example. In this paper, the firms which accessed the sectoral funds are compared with the ones which did not, based upon the path followed by their indicators of technological efforts (R&D inputs) and results (R&D outputs). The control group was defined using a Propensity Score Matching (PSM) procedure aiming at reducing the selection bias that makes firms which accessed the funds follow a different path when compared to the ones that did not. Percentage differencein- differences indicate a significant detachment between the technological efforts of the treatment and control groups and permit the hypothesis of crowding out to be rejected. The growth differential on the PoTec variable – the proxy for technological efforts – is estimated in 6.8 p.p. in the first year, 11.5 in the second, 15.7 p.p. in the third and 26.7 p.p. in the fourth year after the access to the funds. The sectoral funds also presented a significant and positive impact on the number of employees, although only a marginally significant impact on high-tech exports was observed four years after the treatment. Additionally, a preliminary analysis of the impacts of the different instruments that form the sectoral funds suggests that most impacts observed in the technological efforts can be associated to the credit at favorable conditions

Utilizando aprendizado de máquina para estimação do spread das instituições financeiras nos empréstimos do BNDES

É permitida a reprodução deste texto e dos dados nele contidos, desde que citada a fonte. Reproduções para fins comerciais são proibidas.Bibliografia: p. 101-10

An estimate of the number of tropical tree species

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e. at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa

Narcissism and the strategic pursuit of short-term mating : universal links across 11 world regions of the International Sexuality Description Project-2.

Previous studies have documented links between sub-clinical narcissism and the active pursuit of short-term mating strategies (e.g., unrestricted sociosexuality, marital infidelity, mate poaching). Nearly all of these investigations have relied solely on samples from Western cultures. In the current study, responses from a cross-cultural survey of 30,470 people across 53 nations spanning 11 world regions (North America, Central/South America, Northern Europe, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, Southeast Asia, and East Asia) were used to evaluate whether narcissism (as measured by the Narcissistic Personality Inventory; NPI) was universally associated with short-term mating. Results revealed narcissism scores (including two broad factors and seven traditional facets as measured by the NPI) were functionally equivalent across cultures, reliably associating with key sexual outcomes (e.g., more active pursuit of short-term mating, intimate partner violence, and sexual aggression) and sex-related personality traits (e.g., higher extraversion and openness to experience). Whereas some features of personality (e.g., subjective well-being) were universally associated with socially adaptive facets of Narcissism (e.g., self-sufficiency), most indicators of short-term mating (e.g., unrestricted sociosexuality and marital infidelity) were universally associated with the socially maladaptive facets of narcissism (e.g., exploitativeness). Discussion addresses limitations of these cross-culturally universal findings and presents suggestions for future research into revealing the precise psychological features of narcissism that facilitate the strategic pursuit of short-term mating

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions