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This paper applies the dynamic linear model (DLM) estimated based on the Bayesian approach to project electricity consumption for five Brazilian regional units. The appeal for the use of DLM in the case of energy consumption is due to the fact that in this model the adjustment occurs in the unit of time ensuring more accurate projections in series with a high degree of variability, such as energy consumption. The results corroborated the expectation regarding the adequacy of DLM for the purpose of making projections. The different forecast validation criteria calculated for a 12-month horizon showed very satisfactory results. In all cases, MLD had a forecast error within the 3% range, taken as a reference for the utilities. In the case of the Center, Northeast and South regions, this indicator was even lower. We tested the robustness of the MDL using a model panel data with random coefficients (MRC) that allows to obtain a set of distinct coefficients for each region, but within a common structure. Regarding forecasting, MRC performance was also reasonable, even underperforming DLM. With the exception of the Southeast region, MRC's Mape was below or in the 3% range for the other regions.

Na última década, registou-se um aumento exponencial de investidores nos mercados das commodities, uma vez que estas passaram a ser transacionadas como ativos financeiros. Este estudo tem como objetivo perceber se existe especulação excessiva nos contratos de futuros, analisando as transações dos contratos de futuros sobre um conjunto representativo de commodities tais como o petróleo bruto, o gás natural, o paládio, o milho e o café. Mais especificamente pretende-se saber se a existência de especuladores afeta a rendibilidade e a volatilidade dos contratos de futuros. Os resultados encontrados são os seguintes: 1. No presente período de recessão económica mundial verifica-se influência na variação do preço dos contratos de futuros face aos seus valores fundamentais. 2. Os contratos analisados são dominados tanto nas posições de compra como nas posições de venda por hedgers, à exceção do contrato do paládio que é dominado nas posições de compra por especuladores, e do gás natural nas posições de venda que é dominado por especuladores no período entre junho de 2008 e abril de 2012. 3. Os especuladores têm mais posições de compra do que de venda em todas as commodities; os investidores comerciais têm mais posições de venda do que de compra, exceto no gás natural, em que se verifica a situação contrária, tanto nos investidores comerciais como não comerciais. 4. Usando um índice de especulação de Working (1962), conclui-se que o nível de especulação é equilibrado e que não existe excesso de especulação, à exceção dos contratos do petróleo bruto e do café. In the last decade, there has been an exponential increase of commodity market traders. This is due to the fact that commodities are now traded as financial assets. This study aims to understand if there is excessive speculation in futures contracts by analyzing transactions of these contracts on a representative set of commodities such as crude oil, natural gas, palladium, corn and coffee. It strives to know whether the existence of speculators directly affects the returns and volatility of futures contracts. The results are as follows: 1. In this period of global economic recession there is influence on the variation in the price of futures contracts against their core values. 2. The analyzed contracts are dominated by hedgers in both long and short positions except for the palladium contract which is dominated in long positions by speculators and natural gas contracts which are dominated in short positions during the period of June 2008 through April 2012. 3. Speculators have more long than short positions in all commodities; commercial traders have more short than long positions except in natural gas, where the opposite is verified, both in commercial and non-commercial traders. 4. Using the Working (1962) speculation index, it is concluded that the level of speculation is balanced and that there is not too much speculation, with the exception of oil and coffee contracts.