Smokers do not burden the health service, green voters do more damage to the environment than other people, and there are no alligators in the sewers of New York. This, anyway, is what statisticians Walter Kramer and Gotz Trenkler of the University of Dortmund would have us believe.

They have just published their reasoning for these and 500 other unlikely facts in a Dictionary of Popular Misconceptions, which aims to explode all misunderstandings, flaws of reasoning, prejudices, urban myths and wishful thinking. The book is fast becoming a bestseller in Germany, although it has also brought some disapproving frowns from various colleagues in the serious academic establishment.

"Germany is not like the United States where it is considered honourable to write a popular academic book," admits Professor Kramer, whose other published titles include the less populist The Linear Regression Model Under Test.

The idea for the lexicon originated from a serious study on smoking by Professor Kramer, who specialises in health economics and finance. He found that cigarette smoking, rather than increasing health service costs, tended to ease the strain on it because smokers die younger. "When it was published it attracted so many protests that I thought there must be more to this," Professor Kramer said.

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Fifteen years later he and Dr Trenkler have published their collection of misconceptions from the fields of economics, technology, science, politics and history - complete with explanations and supporting references ranging from serious scientific journals and historical sources to the Guinness Book of Records.

Some seem specifically aimed at goading modern German virtues: the environmentally unfriendly side of green voters is based on a German study which found that greens are statistically more likely to take exotic holidays involving long air flights, and to eat out in expensive restaurants which use imported ingredients - altogether more damaging to the environment than a dozen Big Macs.

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And the authors cited numerous academic studies to support their claim that fast food is not unhealthy. "A Big Mac contains too much fat and too little roughage, but it has more vitamins, calcium and iron than other dishes which cost ten times as much."

But they enter more dangerous territory when they tackle academically controversial issues claiming that alcohol is not fundamentally unhealthy, that workers are not exploited under capitalism and that rent controls actually raise the cost of rents.

Some critics have sniffed that many of the authors' claims were obvious: everyone knows, they say, that spinach is not healthier than other vegetables, that Hamburg has more bridges than Venice (2,123 against 398) and that camels' humps do not store water but fat.

But the authors counter that the book was not intended for experts: "Our susceptibility to errors does not depend on our intelligence quota, if some readers find this comforting . . . The surprising thing about such misconceptions is not that they exist, but how persistent they are."

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The authors believe some myths survive because they are useful, underline or cash in on interests, or because people want to believe them. Others, such as the urban myth that there are alligators in the sewers of New York, allow people unconsciously to live out their fears and aggressions. Others, such as the basic dangers of alcohol, are paternalistic, supposedly aimed at protecting the masses, they claim.

"A book for know-it-alls," said a review in Buchjournal adding pompously: "Errare humanum est."

But the weekly Die Zeit was more generous. Reviewer Wolfgang Blum admitted it was "the first lexicon this critic had ever read from A to Z".