830 resultados para Unit root analysis
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Description based on: 1982; title from cover.
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"For administrative use only."
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Report for 1937/30 covers period July 1937-Dec. 1939.
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Category-management models serve to assist in the development of plans for pricing and promotions of individual brands. Techniques to solve the models can have problems of accuracy and interpretability because they are susceptible to spurious regression problems due to nonstationary time-series data. Improperly stated nonstationary systems can reduce the accuracy of the forecasts and undermine the interpretation of the results. This is problematic because recent studies indicate that sales are often a nonstationary time-series. Newly developed correction techniques can account for nonstationarity by incorporating error-correction terms into the model when using a Bayesian Vector Error-Correction Model. The benefit of using such a technique is that shocks to control variates can be separated into permanent and temporary effects and allow cointegration of series for analysis purposes. Analysis of a brand data set indicates that this is important even at the brand level. Thus, additional information is generated that allows a decision maker to examine controllable variables in terms of whether they influence sales over a short or long duration. Only products that are nonstationary in sales volume can be manipulated for long-term profit gain, and promotions must be cointegrated with brand sales volume. The brand data set is used to explore the capabilities and interpretation of cointegration.
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This paper reinvestigates the energy consumption-GDP growth nexus in a panel error correction model using data on 20 net energy importers and exporters from 1971 to 2002. Among the energy exporters, there was bidirectional causality between economic growth and energy consumption in the developed countries in both the short and long run, while in the developing countries energy consumption stimulates growth only in the short run. The former result is also found for energy importers and the latter result exists only for the developed countries within this category. In addition, compared to the developing countries, the developed countries' elasticity response in terms of economic growth from an increase in energy consumption is larger although its income elasticity is lower and less than unitary. Lastly. the implications for energy policy calling for a more holistic approach are discussed. (c) 2006 Elsevier Ltd. All rights reserved.
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Research on women’s employment has proliferated over recent decades, often under a perspective that conceptualizes female labour market activity as independent of male presences and absences in the productive and reproductive spheres. In the face of these approaches, the article argues the need to focus on the couple as the unit of analysis of work-life articulation. After referring to the main theoretical arguments that, from a gender perspective within labour studies, have pointed out the relevance of placing the household as the central space for the analysis of the sexual division of labour, the article reviews different empirical contributions that have incorporated such perspective in the international literature. Next, the state of the art in the Spanish literature is presented, before arguing the desirability of applying such framework of analysis to the study of employment and care work in Spanish households, which are at present undergoing major transformations.
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The main objetive of this research is to evaluate the long term relationship between energy consumption and GDP for some Latin American countries in the period 1980-2009 -- The estimation has been done through the non-stationary panel approach, using the production function in order to control other sources of GDP variation, such as capital and labor -- In addition to this, a panel unit root tests are used in order to identify the non-stationarity of these variables, followed by the application of panel cointegration test proposed by Pedroni (2004) to avoid a spurious regression (Entorf, 1997; Kao, 1999)
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Mestrado em Finanças
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The analysis of interviews with open-ended questions is a common practice amongst researchers in the field of Management. The difficulty therein is to convert the linguistic data into categories or quantitative values for subsequent statistical treatment. Proposals made to this end generally entail counting lexical occurrences which, since they are founded on previously established meanings, fail to include semantic associations made by interviews. This article aims to present an analysis tool comprising a set of techniques apt to generate linguistic units that can be statistically described, compared, modeled and inferred: the Quantitative Propositional Analysis (QPA), Its main difference from other such methods lies in the choice of a proposition - and not the lexical unit - as analysis unit. We present the application of this method through a study about the international expansion of retail firms.
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We have investigated the ovariectomy effects on the cardiovascular autonomic adaptations induced by aerobic physical training and the role played by nitric oxide (NO). Female Wistar rats (n =70) were divided into five groups: Sedentary Sham (SS): Trained Sham (TS); Trained Hypertensive Sham treated with N(C)-nitro-L-arginine methyl ester (L-NAME) (THS): Trained Ovariectomized (TO); and Trained Hypertensive Ovariectomized treated with L-NAME (THO). Trained groups were submitted to a physical training during 10 weeks. The cardiovascular autonomic control was investigated in all groups using different approaches: 1) pharmacological evaluation of autonomic tonus with methylatropine and propranolol; 2) analysis of heart rate (HR) and systolic arterial pressure (AP) variability; 3) spontaneous baroreflex sensitivity (BRS) evaluation. Hypertension was observed in THS and THO groups. Pharmacological analysis showed that TS group had increased predominance of autonomic vagal tonus compared to SS group. HR and intrinsic HR were found to be reduced in all trained animals. TS group, compared to other groups, showed a reduction in LF oscillations (LF=0.2-0.75 Hz) of pulse interval in both absolute and normalized units as well as an increase in HF oscillations (HF=0.75-2.50 Hz) in normalized unit. FIRS analysis showed that alpha-index was different between all groups. TS group presented the greatest value, followed by the TO, SS. THO and THS groups. Ovariectomy has negative effects on cardiac autonomic modulation in trained rats, which is characterized by an increase in the sympathetic autonomic modulation. These negative effects suggest NO deficiency. In contrast, the ovariectomy seems to have no effect on AP variability. (C) 2008 Elsevier B.V. All rights reserved.
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Objectives. The objectives of this study were to assess the accuracy of working length determination using 3 electronic apex locators and direct digital radiography and to compare the results with those obtained using the visual method (control measurement). Study design. Twenty extracted human maxillary premolars were selected: 17 two-rooted and 3 single-rooted (total of 37 canals). Working length was measured using electronic apex locators Elements Diagnostic, Root ZX, and Just II. Subsequently, teeth were positioned in the alveolar bone of a dry skull and submitted to direct digital radiography. A variation of +/- 1 mm was considered as acceptable. Results were analyzed using the Wilcoxon and the chi(2) tests. Results. Results presented an accuracy of 94.6% for Elements Diagnostic, 91.9% for Root ZX, 73.0% for Just II, and 64.9% for direct digital radiography when considering the margin of +/- 1 mm in relation to the control measurement. Comparisons with the actual control measurements resulted in accuracy results of 13.51%, 13.51%, 10.10%, and 2.70%, respectively. Conclusions. Root ZX and Elements Diagnostic are more accurate in determining working length when compared with Just II and Schick direct digital radiography. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:e44-e49)
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Background: Low-fluoride dentifrices have been suggested as alternatives to reduce dental fluorosis risk, but there is no consensus regarding their clinical effectiveness, which has been suggested to be increased when their pH is acidic. Aims: This single-blind randomized clinical trial evaluated the caries increment during the use of a low-fluoride acidic liquid dentifrice. Methods: Four-year-old schoolchildren (n = 1,402) living in a fluoridated area (0.6-0.8 ppm F) were randomly allocated to 4 groups differing according to the type of dentifrice used over a 20-month period. Group 1 (n = 345): liquid dentifrice, 1,100 ppm F, pH 4.5. Group 2 (n = 343): liquid dentifrice, 1,100 ppm F, pH 7.0. Group 3 (n = 354): liquid dentifrice, 550 ppm F, pH 4.5. Group 4 (n = 360): toothpaste, 1,100 ppm F, pH 7.0. At baseline and after 20 months, clinical examinations were conducted (dmfs index) and caries increment was calculated. Data were analysed by GLM procedure using classrooms (cluster) as unit of analysis (p < 0.05). Results: The mean +/- SD (95% CI) net increments found were as follows. Group 1: 2.06 +/- 2.38 (1.8-2.3); group 2: 2.08 +/- 2.87 (1.7-2.4); group 3: 2.05 +/- 2.79 (1.7-2.4), and group 4: 2.08 +/- 2.34 (1.8-2.4). No significant differences were detected among the groups. Conclusion: In a population with high caries risk living in a fluoridated area, as the selected sample, and according to the present protocol, the low-fluoride acidic liquid dentifrice seems to lead to similar caries progression rates as conventional 1,100 ppm F toothpaste. Copyright (C) 2010 S. Karger AG, Basel
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Os Hospitais, equipamentos de interesse público, são edifícios cujos desempenho e disponibilidade das suas instalações e equipamentos podem comprometer a prestação de cuidados de saúde, pelo que nestes estabelecimentos, a Manutenção Preventiva assume um papel relevante. Nesse sentido, pretendeu-se nesta dissertação definir uma estratégia específica que permita efectuar o planeamento da manutenção preventiva de um edifício hospitalar, enquanto infraestrutura para desenvolvimento da actividade clínica. Para tal, foi efectuada uma pesquisa bibliográfica, com a qual se identificaram conceitos de manutenção e requisitos a serem tidos em conta na manutenção de edifícios hospitalares. Foi efectuada uma caracterização genérica do objecto de manutenção, limitada no âmbito desta dissertação às principais componentes dos sistemas de construção e das instalações de águas e esgotos, que podem integrar um edifício hospitalar actual, atendendo às especificações e recomendações técnicas vigentes para este tipo de edifícios. Foram identificados os objectivos e requisitos de manutenção nestes edifícios, estabelecidos pelas condições de funcionamento pretendidas, pelos critérios de durabilidade exigidos pelo Dono de Obra, pelo nível de desempenho funcional requerido para as suas componentes e pelo grau de operacionalidade imposto nas suas diferentes unidades funcionais. Tendo em consideração que a criticidade de uma componente não depende só do contexto operacional da área funcional em se insere mas também das consequências que o seu estado de funcionamento pode acarretar para a unidade funcional. Foi exemplificada a análise dos modos de falha, sua criticidade e seus efeitos para hierarquização do risco associado nas componentes estudadas. As fichas exemplificativas dos planos de manutenção preventiva, que se apresentam no âmbito desta dissertação para algumas componentes básicas, integram acções e procedimentos que derivam de uma análise aos seus modos de falha e seus efeitos, bem como de recomendações técnicas exigências da regulamentação em vigor.
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The central place hospitals occupy in health systems transforms them into prime target of healthcare reforms. This study aims to identify current trends in organizational structure change in public hospitals and explore the role of accounting in attempts to develop controls over professionals within public hospitals. The analytical framework we proposed crosses the concept of “new professionalism” (Evetts, 2010), with the concept of “accounting logic” for controlling professionals (Broadbent and Laughlin, 1995). Looking for a more holistic overview, we developed a qualitative and exploratory study. The data were collected trough semi-structured interviews with doctors of a clinical hospital unit. Content analysis suggests that, although we cannot say that there is a complete and generalized integration of accounting information in the clinical decisions, important improvement has been made in that area. Despite the extensive literature developed on this topic, there is any empirical studies of authors are aware that allow us to realize how real doctors in reals day-to-day work integrated these trends of change in theirs clinical decisions.
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OBJECTIVE: To identify clustering areas of infants exposed to HIV during pregnancy and their association with indicators of primary care coverage and socioeconomic condition. METHODS: Ecological study where the unit of analysis was primary care coverage areas in the city of Porto Alegre, Southern Brazil, in 2003. Geographical Information System and spatial analysis tools were used to describe indicators of primary care coverage areas and socioeconomic condition, and estimate the prevalence of liveborn infants exposed to HIV during pregnancy and delivery. Data was obtained from Brazilian national databases. The association between different indicators was assessed using Spearman's nonparametric test. RESULTS: There was found an association between HIV infection and high birth rates (r=0.22, p<0.01) and lack of prenatal care (r=0.15, p<0.05). The highest HIV infection rates were seen in areas with poor socioeconomic conditions and difficult access to health services (r=0.28, p<0.01). The association found between higher rate of prenatal care among HIV-infected women and adequate immunization coverage (r=0.35, p<0.01) indicates that early detection of HIV infection is effective in those areas with better primary care services. CONCLUSIONS: Urban poverty is a strong determinant of mother-to-child HIV transmission but this trend can be fought with health surveillance at the primary care level.