In terms of imported oil Cuba began first to buy oil from the open market in the beginning of 1990s. In the more recent past, however, a significant change with the oil imports was brought by the favourable trade terms developed with Venezuela (after Hugo Chavez was elected as president in 1998). Some of the oil from Venezuela is financed by loans, part is a barter trade involving about 20,000 Cuban medical professionals who work in Venezuela, and some oil is provided as a grant , 80. Although on the one hand the deal with Venezuela has been essential for the recovery of the Cuban economy, on the other hand it PCI32765 has once again made Cuba dependent on subsidized imported oil.
3. Material and methods
The method of ASA is a complete decomposition analysis in order to divide the total change of researched variable into different components which are called factors. The sum of all identified and decomposed factors equals to the total change of variable under investigation.
In the literature, different methods of decomposition analysis have been grouped into additive and multiplicative ones and those based on different index values such as Divisia index, Laspeyres index, Marshall–Edgeworth index or Shapley index [25,26]. The increasing amount of empirical research is combined to a fact ligaments a widening variety of different decomposition methods has been developed giving reason to methodological discussion. For reviews of different decomposition methods, see e.g. ,  and . Different decomposition methods may give different results with a same dataset, and one method may provide a larger residual term than another.