Governments talk constantly of lifelong learning, of knowledge economies and of upgrading skills.
But no one knows exactly how or to what extent education helps economies grow, or how much it costs. Assessing its impact is a ''devilishly difficult'' problem, according to Andrew Wyckoff, who is in charge of economic analysis and statistics at the Organization for Economic Cooperation and Development in Paris. The 29-nation organization is the world's leading source of comparative international data, but this is one area where the figures baffle as much as shed light. For example, the United States lags far behind other developed countries in investment and achievement at high school level, yet has the world's most vibrant economy. The old Soviet Union poured vast resources into education, yet its economy was a basket case.