Why Ukraine isn't mentioned explicitly the explanation of the lack of medals for Ukraine can be inferred from this article
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I've got a couple of other theories for some of the variation from the model. Russia's athletic performance is in relative decline because the whole country is in relative decline. In the post-Soviet era, Russia's health, life expectancy, and population have declined. In the past two decades, many of its most ambitious citizens, including world-class athletes and their families, have emigrated. "Emigration probably has some impact," said Johnson. "For any nation where quality of life is diminishing, people with world-class opportunities leave." In Beijing, for example,gymnast Nastia Liukin, a Moscow native, won medals for the United States, not Russia. Italy, another country in economic and demographic decline, similar fell on its face in Vancouver. The model, which perhaps gave too much weight to Italy's impressive 2006 Turin performance, projected the Italians would win 19 medals. They took home only five."
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"As it was for the Austrian skiers, the Vancouver Olympics were a little chastening for Prof. Johnson and his model. Over the past few Olympics, the model has a 94 percent correlation with the actual medal count per country and about an 88 percent correlation with the actual gold medal haul per country. But this year, not so much. "The predictions were less accurate this year than in any previous Olympics for which we've run numbers," Johnson said. "That suggests to me that something changed and these games were unusual.""
