2 resultados para Random effects

em Repositório Científico da Universidade de Évora - Portugal


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No presente estudo procuramos analisar os determinantes do crescimento das empresas familiares portuguesas, através de uma amostra de empresas familiares membros da Associação de Empresas Familiares, durante o período de 2006 a 2014. Com vista ao teste das hipóteses em estudo foram utilizados dados em painel, com modelos de efeitos fixo e aleatório. A variável dependente definida foi o crescimento das vendas. As variáveis independentes definidas foram: dimensão; idade; endividamento; endividamento de curto prazo; endividamento de médio longo prazo; produtividade da mão-de-obra; estrutura do ativo; variável dummy da crise financeira; variável dummy da administração pertencer à família; e variável dummy do género do administrador. Os resultados obtidos confirmam a dimensão, a idade e o endividamento como determinantes do crescimento; ABSTRACT: In the present study we analyzed the determinants of growth of family businesses through a sample of family businesses members of the Family Business Association, during the period between 2006 and 2014. In order to test the hypotheses under study were used panel data, with models of fixed and random effects. The Sales growth was defined as the dependent variable. The independent variables were defined: size; age; debt; short-term debt; medium and long term debt; labor productivity; asset structure; dummy variable of the financial crisis; dummy administration belong to the family; and dummy administrator gender variable. The results confirm the size, age, and debt as determinants of growth.

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This study’s main goal was to evaluate the thermoregulatory responses velocity through the variation of rectal temperature (RT), related to the thermolytic pathways, respiratory rate (RR) and sweating rate (SR) among different sheep breeds. Ninety female sheep, eighteen of each breed: Santa Ines and Morada Nova (Brazilian hair breeds), Texel, Suffolk and Ile de France (wool breeds) were challenged during three non-consecutive summer days (22◦42′S, 47◦18′W, and 570m of altitude, maximum air temperature of 33.5◦C, average relative humidity of 52±6.9%). The physiological variables were registered at 0800h (T1), 1300 h (T2: after 2 h of shade rest), 1400 h (T3) (after one hour of sun exposure) and in the shade at 1415 h (T4), 1430 h (T5), 1445 h (T6) and 1500 h (T7) and a thermotolerance index (TCI) was calculated as (10-(T7 to T4)-T1). The statistical analysis was performed by a mathematical model including the fixed effects of breeds and time frames, and the interaction between these effects, besides random effects such as animal and day. The Santa Ines breed presented the lowest RT after sun exposure (39.3 ± 0.12 ◦ C; P < 0.05) and it was the only one to recover morning RT 60 min after heat stress (38.7 and 38.9 for 1300 h and 1500 h; P > 0.05). Hair breeds presented RR lower (P < 0.05) than wool breeds. Although thick wool or hair thickness differs among and within hair and wool breeds (P < 0.05), SR did not differ among breeds and time (227.7 ± 16.44 g m−2 h−1 ; P > 0.05). The thermotolerance index did not differ among breeds, but it showed similar response (P > 0.05) 45 min or 1 h of shade after sun exposure. One week post shearing is not enough to wool breeds present to show thermotolerance similar to hair breeds.