None of the measured variables in the freedom index relate to health care per se.

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Messrs Frey and Stutzer find that a one-point increase in this democracy index, after stripping out the effects of the other variables, increases the share of people who say they are very happy by 2.7 percentage points.

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They use a forecasting model that relies, in particular, on the close historical relationship between company profits and two variables, total corporate investment in equipment and the commodity-price index published by The Economist.

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Google's more than 10, 000 networked computers crawl through an index to those 3 billion pages, rank them using an equation that includes 500 million variables and spit out up to a few thousand listings.

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Tendai Musikavanhu, president of Old Mutual Global Index Trackers, part of the Old Mutual investment and insurance banking family, says there are too many variables at play to know for sure.

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