900 resultados para meta-regression analysis
Angel Investing in Finland: An Analysis Based on Agency Theory and the Incomplete Contracting Theory
Resumo:
Wealthy individuals - business angels who invest a share of their net worth in entrepreneurial ventures - form an essential part of an informal venture capital market that can secure funding for entrepreneurial ventures. In Finland, business angels represent an untapped pool of capital that can contribute to fostering entrepreneurial development. In addition, business angels can bridge knowledge gaps in new business ventures by means of making their human capital available. This study has two objectives. The first is to gain an understanding of the characteristics and investment behaviour of Finnish business angels. The strongest focus here is on the due diligence procedures and their involvement post investment. The second objective is to assess whether agency theory and the incomplete contacting theory are useful theoretical lenses in the arena of business angels. To achieve the second objective, this study investigates i) how risk is mitigated in the investment process, ii) how uncertainty influences the comprehensiveness of due diligence as well as iii) how control is allocated post investment. Research hypotheses are derived from assumptions underlying agency theory and the incomplete contacting theory. The data for this study comprise interviews with 53 business angels. In terms of sample size this is the largest on Finnish business angels. The research hypotheses in this study are tested using regression analysis. This study suggests that the Finnish informal venture capital market appears to be comprised of a limited number of business angels whose style of investing much resembles their formal counterparts’. Much focus is placed on managing risks prior to making the investment by strong selectiveness and by a relatively comprehensive due diligence. The involvement is rarely on a day-to-day basis and many business angels seem to see board membership as a more suitable alternative than involvement in the operations of an entrepreneurial venture. The uncertainty involved does not seem to drive an increase in due diligence. On the contrary, it would appear that due diligence is more rigorous in safer later stage investments and when the business angels have considerable previous experience as investors. Finnish business angels’ involvement post investment is best explained by their degree of ownership in the entrepreneurial venture. It seems that when investors feel they are sufficiently rewarded, in terms of an adequate equity stake, they are willing to involve themselves actively in their investments. The lack of support for a relationship between increased uncertainty and the comprehensiveness of due diligence may partly be explained by an increasing trend towards portfolio diversification. This is triggered by a taxation system that favours investments through investment companies rather than direct investments. Many business angels appear to have substituted a specialization strategy that builds on reducing uncertainty for a diversification strategy that builds on reducing firm specific (idiosyncratic) risk by holding shares in ventures whose returns are not expected to exhibit a strong positive correlation.
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This paper analyzes the path of the international expansion of Grupo Arcor, an Argentine multinational company specializing in confectionery. The objective is to entify corporate strategies and business learning that led this Latin American firm to establish itself as one of the leading manufacturers in confectionery industry ,particularly in the 21st Century. The analysis is primarily qualitative in order to identify the economic dimension as a determinant in the internationalization process; a processbased approach from the Uppsala Model is used for this. However, the study is also complemented with a regression analysis to test if the firm was driven to expand internationally by the expectations on the degree of globalization of the industry and the accumulation of experience in foreign markets, and if the company was influenced by psychic distance in choosing the location of its investment; given the influence of these variables in Grupo Arcor business strategies. Our findings suggest that Grupo Arcor, was able to become global due to strategies such as vertical integration, diversification of products and geographical markets (based on psychic distance) and indeed some strategies were consequence of the globalization of the sector and the accumulation of experience in foreign markets.
Resumo:
This study examined the economic potential of fish farming in Abeokuta zone of Ogun State in the 2003 production season. Descriptive statistics cost returns and multiple regression analysis were used in analyzing the data. The farmers predominantly practiced monoculture. Inefficiency in the use of pond size, lime and labour with over-utilization of fingerlings stocked was revealed by the study. The average variable cost of N124.67 constituted 45% of the total while average fixed cost was N149.802.67 per average farm size. Fish farming was found to be a profitable venture in the study area with a net income of N761, 400.58 for an average pond size of 301.47sq.m. Based on these findings, it is suggested that for profit maximization, the fish farm will have to increase the level of their use of fingerlings and fertilizers and decrease the use of lime labour and pond size
Resumo:
O transtorno do estresse pós-traumático (TEPT) e alterações lipídicas são as temáticas principais dessa Dissertação. Seu objetivo principal foi investigar a associação entre o TEPT e as concentrações séricas de colesterol total (CT), lipoproteína de baixa densidade (LDL), lipoproteína de alta densidade (HDL) e triglicerídeos (TG) através de uma revisão sistemática da literatura seguida de metanálise. Adicionalmente, a relação entre essas variáveis lipídicas e os grupos de sintomas do TEPT revivescência, esquiva/entorpecimento emocional e hiperestimulação autonômica foi avaliada em um segundo estudo com dados primários. A metanálise incluiu 18 artigos, totalizando 2.110 indivíduos com TEPT e 17.550 indivíduos sem TEPT. As diferenças de médias ponderadas (DMP) mg/dL dos parâmetros lipídicos foram calculadas por modelos de efeitos aleatórios e modelos de meta-regressão foram ajustados para investigar possíveis fontes de heterogeneidade. O estudo encontrou que o TEPT foi associado a um pior perfil lipídico quando comparados a controles sem o transtorno (DMPCT= 20,57, IC 95% 12,21 28,93; DMPLDL= 12,11, IC 95% 5,89 18,32; DMPHDL= -3,73, IC 95% -5,97 -1,49; DMPTG= 35,87, IC 95% 21,12 50,61). A heterogeneidade estatística entre os resultados dos estudos foi alta para todos os parâmetros lipídicos e a variável que mais pareceu explicar essas inconsistências foi idade. O segundo artigo faz parte de um estudo maior conduzido em 2004 com 157 policiais do sexo masculino do Batalhão de Choque da Polícia Militar do Estado de Goiás (BPMCHOQUE). Somente oficiais de férias ou em dispensa inclusive dispensa médica não foram avaliados. O instrumento utilizado para o rastreio do TEPT foi a versão em português para civis da Post-Traumatic Stress Disorder Checklist (PCL-C). Trinta e nove participantes (25%) foram excluídos do estudo: dois porque falharam no preenchimento dos questionários e 37 cujas amostras de sangue não foram coletadas por vários motivos. Neste trabalho, encontrou-se uma forte correlação positiva entre as concentrações séricas de CT e LDL com o grupo de sintomas de hiperestimulação autonômica, somente no grupo TEPT: ρ= 0,89 (p<0,01) e ρ =0,92 (p<0,01), respectivamente. Em suma, espera-se que os resultados dessa Dissertação possam colaborar para o estabelecimento de um melhor acompanhamento clínico de pacientes com TEPT, particularmente porque estes parecem estar sob um maior risco de doenças cardiovasculares devido a um pior perfil lipídico.
Resumo:
O transtorno de estresse pós-traumático (TEPT) é um transtorno de ansiedade que pode ser desenvolvido após a ocorrência de um evento traumático, e que costuma vir acompanhado de um significativo comprometimento da qualidade de vida. Indivíduos diagnosticados com o TEPT apresentam níveis de frequência cardíaca mais elevados em situações de exposição a eventos estressores, como sons e imagens que relembram a experiência traumática. No entanto, estudos que avaliaram a frequência cardíaca no momento do trauma como preditor do desenvolvimento de TEPT não apresentam resultados consistentes. Os objetivos deste trabalho foram: verificar se frequência cardíaca (FC) peritraumática de repouso, após exposição ao trauma, é um fator preditor para o desenvolvimento do TEPT e para a gravidade dos sintomas de TEPT em adultos. Foi realizada uma revisão sistemática, seguida de metanálise, utilizando-se as bases eletrônicas PUBMED, LILACS, PILOTS, PsycoINFO e Web of Science. Foram incluídos 17 estudos nesta revisão sistemática. Os resultados de dez estudos foram utilizados para a metanálise das diferenças de médias de FC combinada. Oito estudos foram utilizados para a metanálise das correlações entre a FC e a gravidade dos sintomas de TEPT. Modelos de meta-regressão foram ajustados para identificar variáveis que pudessem explicar a heterogeneidade entre os estudos. A FC peritraumática no grupo de pacientes com TEPT é, em média, 3,98 batimento por mimuto (bpm) (p=0,04) maior em comparação com aqueles sem o transtorno, e o coeficiente de correlação de Pearson combinado foi de 0,14 (p=0,05).Consistente com a hipótese levantada, a frequência cardíaca peritraumática de repouso foi maior em indivíduos que desenvolveram o TEPT. Contudo, mensuração mais próxima do evento traumático e a exclusão de casos dissociativos poderão ampliar a magnitude do efeito encontrado, tornando este biomarcador simples e facilmente obtido um preditor clinicamente útil do desenvolvimento de TEPT.
Resumo:
Bottlenose dolphins (Tursiops truncatus) inhabit estuarine waters near Charleston, South Carolina (SC) feeding, nursing and socializing. While in these waters, dolphins are exposed to multiple direct and indirect threats such as anthropogenic impacts (egs. harassment with boat traffic and entanglements in fishing gear) and environmental degradation. Bottlenose dolphins are protected under the Marine Mammal Protection Act of 1972. Over the years, the percentage of strandings in the estuaries has increased in South Carolina and, specifically, recent stranding data shows an increase in strandings occurring in Charleston, SC near areas of residential development. During the same timeframe, Charleston experienced a shift in human population towards the coastline. These two trends, rise in estuarine dolphin strandings and shift in human population, have raised questions on whether the increase in strandings is a result of more detectable strandings being reported, or a true increase in stranding events. Using GIS, the trends in strandings were compared to residential growth, boat permits, fishing permits, and dock permits in Charleston County from 1994-2009. A simple linear regression analysis was performed to determine if there were any significant relationships between strandings, boat permits, commercial fishing permits, and crabpot permits. The results of this analysis show the stranding trend moves toward Charleston Harbor and adjacent rivers over time which suggests the increase in strandings is related to the strandings becoming more detectable. The statistical analysis shows that the factors that cause human interaction strandings such as boats, commercial fishing, and crabpot line entanglements are not significantly related to strandings further supporting the hypothesis that the increase in strandings are due to increased observations on the water as human coastal population increases and are not a natural phenomenon. This study has local and potentially regional marine spatial planning implications to protect coastal natural resources, such as the bottlenose dolphin, while balancing coastal development.
Resumo:
The spatial and temporal dynamics of physical variables, inorganic nutrients and phytoplankton chlorophyll a were investigated in Xiangxi Bay from 23 Feb. to 28 Apr. every six days, including one daily sampling site and one bidaily sampling site. The concentrations of nutrient variables showed ranges of 0.02-3.20 mg/L for dissolved silicate (Si); 0.06-2.40 mg/L for DIN (NH4N + NO2N + NO3N); 0.03-0.56 mg/L for PO4P and 0.22-193.37 mu g/L for chlorophyll a, respectively. The concentration of chlorophyll a and inorganic nutrients were interpolated using GIS techniques. The results indicated that the spring bloom was occurred twice in space during the whole monitoring period (The first one: 26 Feb.-23 Mar.; the second one: 23 Mar.-28 Apr.). The concentration of DIN was always high in the mouth of Xiangxi Bay, and PO4P was high in the upstream of Xiangxi Bay during the whole bloom period. Si seems no obvious difference in space in the beginning of the spring bloom, but showed high heterogeneity in space and time with the development of spring bloom. By comparing the interpolated maps of chlorophyll a and inorganic variables, obvious consumptions of Si and DIN were found when the bloom status was serious. However, no obvious depletion of PO4P was found. Spatial regression analysis could explained most variation of Chl-a except at the begin of the first and second bloom. The result indicated that Si was the factor limiting Chl-a in space before achieved the max area of hypertrophic in the first and second bloom period. When Si was obviously exhausted, DIN became the factor limiting the Chl-a in space. Daily and bidaily monitoring of Site A and B, representing for high DIN: PO4P ratio and low DIN:PO4P ratio, indicated that the concentration of Si was decreased with times at both site A and B, and the dramatically drop of DIN was found in the end monitoring at site B. Multiple stepwise regression analysis indicated that Si was the most important factor affect the development of spring bloom both at site A and B in time series.
Resumo:
To simplify the abstraction of descriptors, for the correlation analysis of the stability constants of gadolinium(III) complexes and their ligand structures, aiming at gadolinium(III) complexes, we only considered the ligands and ignored the common parts of the structures, i.e., the metal ions. Quantum-chemical descriptors and topological indices were calculated to describe the structures of the ligands. Multiple regression analysis and neural networks were applied to construct the models between the ligands and the stability constants of gadolinium(III) complexes and satisfactory results were obtained.
Resumo:
The A(m) index and molecular connectivity index were used for studying the photoionization sensitivity of some organic compounds in gas chromatography. The analysis of structure-property relationship between the photoionization sensitivity of the compounds and the A(m) indices or molecular connectivity indices has been carried out. The genetic algorighm was used to build the correlation model in this field. The results demonstrate that the property of compounds can be described by both A(m) indices and molecular connectivity indices, and the mathematical model obtained by the genetic algorithm was better than that by multivariate regression analysis.
Resumo:
The shell traits and weight traits are measured in cultured populations of bay scallop, Argopecten irradians. The results of regression analysis show that the regression relationships for all the traits are significant (P < 0.01). The correlative coefficients between body weight, as well as tissue weight with shell length, shell height and shell width are significant (P < 0.05). But the correlative coefficients between the anterior and posterior auricle length with body weight as well as tissue weight are not significant (P > 0.05). The multiple regression equation is obtained to estimate live body weight and tissue weight. The above traits except anterior and posterior auricle length are used for the growth and production comparison among three cultured populations, Duncan's new multiple range procedure analysis shows that all the traits in the Lingshuiqiao (LSQ) population are much more significant than those of the other two populations (P < 0.01), and there is no significant difference between the Qipanmo (QPM) and Dalijia (DLJ) populations in all traits (P > 0.05). The results indicate that the LSQ population has a higher growth rate and is expected to be more productive than the other two populations.
Resumo:
Based on social survey data conducted by local research group in some counties executed in the nearly past five years in China, the author proposed and solved two kernel problems in the field of social situation forecasting: i) How can the attitudes’ data on individual level be integrated with social situation data on macrolevel; ii) How can the powers of forecasting models’ constructed by different statistic methods be compared? Five integrative statistics were applied to the research: 1) algorithm average (MEAN); 2) standard deviation (SD); 3) coefficient variability (CV); 4) mixed secondary moment (M2); 5) Tendency (TD). To solve the former problem, the five statistics were taken to synthesize the individual and mocrolevel data of social situations on the levels of counties’ regions, and form novel integrative datasets, from the basis of which, the latter problem was accomplished by the author: modeling methods such as Multiple Regression Analysis (MRA), Discriminant Analysis (DA) and Support Vector Machine (SVM) were used to construct several forecasting models. Meanwhile, on the dimensions of stepwise vs. enter, short-term vs. long-term forecasting and different integrative (statistic) models, meta-analysis and power analysis were taken to compare the predicting power of each model within and among modeling methods. Finally, it can be concluded from the research of the dissertation: 1) Exactly significant difference exists among different integrative (statistic) models, in which, tendency (TD) integrative models have the highest power, but coefficient variability (CV) ones have the lowest; 2) There is no significant difference of the power between stepwise and enter models as well as short-term and long-term forecasting models; 3) There is significant difference among models constructed by different methods, of which, support vector machine (SVM) has the highest statistic power. This research founded basis in all facets for exploring the optimal forecasting models of social situation’s more deeply, further more, it is the first time methods of meta-analysis and power analysis were immersed into the assessments of such forecasting models.
Resumo:
In regression analysis of counts, a lack of simple and efficient algorithms for posterior computation has made Bayesian approaches appear unattractive and thus underdeveloped. We propose a lognormal and gamma mixed negative binomial (NB) regression model for counts, and present efficient closed-form Bayesian inference; unlike conventional Poisson models, the proposed approach has two free parameters to include two different kinds of random effects, and allows the incorporation of prior information, such as sparsity in the regression coefficients. By placing a gamma distribution prior on the NB dispersion parameter r, and connecting a log-normal distribution prior with the logit of the NB probability parameter p, efficient Gibbs sampling and variational Bayes inference are both developed. The closed-form updates are obtained by exploiting conditional conjugacy via both a compound Poisson representation and a Polya-Gamma distribution based data augmentation approach. The proposed Bayesian inference can be implemented routinely, while being easily generalizable to more complex settings involving multivariate dependence structures. The algorithms are illustrated using real examples. Copyright 2012 by the author(s)/owner(s).
Resumo:
One of the main pillars in the development of inclusive schools is the initial teacher training. Before determining if it is necessary to make changes (and of what type) in training programs or curriculum guides related to the attention to diversity and inclusive education, the attitudes of future education professionals in this area should be analyzed. This includes the identification of the relevant predictors of inclusive attitudes. The research reported in this article pursued this objective, doing so with a quantitative survey methodology based on the use of cross-sectional structured data collection and statistical analyses related to the quality of the attitude questionnaire (factor analysis and Cronbach's alpha), descriptive statistics, correlations, hypothesis tests for difference of means, and regression analysis in order to predict attitudes towards inclusion in education. Firstly, the results show that the participants held very positive attitudes toward the inclusion of students with special educational needs. Particularly, older respondents, those with a longer training and, to a lesser extent, women and those who had been in touch with disabled people stood out within this attitude. Secondly, it is evidenced that self-transcendence values and, more weakly, contact, function as robust predictors of attitudes of future practitioners towards the inclusion of students with special needs. Some applications for the initial professionalization of educators are suggested in the discussion.
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Although it is well known that sandstone porosity and permeability are controlled by a range of parameters such as grain size and sorting, amount, type, and location of diagenetic cements, extent and type of compaction, and the generation of intergranular and intragranular secondary porosity, it is less constrained how these controlling parameters link up in rock volumes (within and between beds) and how they spatially interact to determine porosity and permeability. To address these unknowns, this study examined Triassic fluvial sandstone outcrops from the UK using field logging, probe permeametry of 200 points, and sampling at 100 points on a gridded rock surface. These field observations were supplemented by laser particle-size analysis, thin-section point-count analysis of primary and diagenetic mineralogy, quantitiative XRD mineral analysis, and SEM/EDAX analysis of all 100 samples. These data were analyzed using global regression, variography, kriging, conditional simulation, and geographically weighted regression to examine the spatial relationships between porosity and permeability and their potential controls. The results of bivariate analysis (global regression) of the entire outcrop dataset indicate only a weak correlation between both permeability porosity and their diagenetic and depositional controls and provide very limited information on the role of primary textural structures such as grain size and sorting. Subdividing the dataset further by bedding unit revealed details of more local controls on porosity and permeability. An alternative geostatistical approach combined with a local modelling technique (geographically weighted regression; GWR) subsequently was used to examine the spatial variability of porosity and permeability and their controls. The use of GWR does not require prior knowledge of divisions between bedding units, but the results from GWR broadly concur with results of regression analysis by bedding unit and provide much greater clarity of how porosity and permeability and their controls vary laterally and vertically. The close relationship between depositional lithofacies in each bed, diagenesis, and permeability, porosity demonstrates that each influences the other, and in turn how understanding of reservoir properties is enhanced by integration of paleoenvironmental reconstruction, stratigraphy, mineralogy, and geostatistics.
Resumo:
Objective: To examine the evidence of an association between hypermobility and musculoskeletal pain in children. Methods: A systematic review of the literature was performed using the databases PubMed, EMBASE, NHS Evidence, and Medline. Inclusion criteria were observational studies investigating hypermobility and musculoskeletal pain in children. Exclusion criteria were studies conducted on specialist groups (i.e. dancers) or hospital referrals. Pooled odds ratios (ORs) were calculated using random effects models and heterogeneity was tested using ?(2)-tests. Study quality was assessed using the Newcastle-Ottawa Scale for case-control studies. Results: Of the 80 studies identified, 15 met the inclusion criteria and were included in the review. Of these, 13 were included in the statistical analyses. Analysing the data showed that the heterogeneity was too high to allow for interpretation of the meta-analysis (I(2) = 72%). Heterogeneity was much lower when the studies were divided into European (I(2) = 8%) and Afro-Asian subgroups (I(2) = 65%). Sensitivity analysis based on data from studies reporting from European and Afro-Asian regions showed no association in the European studies [OR 1.00, 95% confidence interval (CI) 0.79-1.26] but a marked relationship between hypermobility and joint pain in the Afro-Asian group (OR 2.01, 95% CI 1.45-2.77). Meta-regression showed a highly significant difference between subgroups in both meta-analyses (p <0.001). Conclusion: There seems to be no association between hypermobility and joint pain in Europeans. There does seem to be an association in Afro-Asians; however, there was a high heterogeneity. It is unclear whether this is due to differences in ethnicity, nourishment, climate or study design.