New treatments become available in accordance with these conceptual changes, and old ones become discarded.
"Structural and conceptual changes will have to be introduced" to raise productivity, Raúl went on.
But he said preliminary planning had evolved to the point where it was important to discuss "important conceptual changes" in talks with these two vital American allies.
As Professor Cromley wrote, "Technological changes supported conceptual changes, and the notion of the roof as servants' territory was gradually reinterpreted after the turn of the century to the dream of a penthouse apartment for well-to-do tenants".
One problem with making major conceptual changes to the calculation of G.D.P. and other macroeconomic data is that we have many decades of economic research correlating it with monetary policy, tax policy and a wide variety of other factors.
However, he took no part in official celebrations marking the anniversary of the start of his communist revolution, where Raúl Castro called for "structural and conceptual changes" to Cuba's economy.
