"'Easy read' should not mean 'easy write,'" they conclude. "And it doesn’t even always mean 'easy read': Readers should apply the same skepticism to the claims of Freakonomics as they would to the much-derided conventional wisdom."

Particularly amusing is when Mr. Gelman and Mr. Fung question Freakonomics author Steven D. Levitt as a "rogue":

We find this odd: He received his Ph.D. from the Massachusetts Institue of Technology, holds the title of Alvin H. Baum Professor of Economics at the University of Chicago and has served as editor of the mainstream Journal of Political Economy. He is a research fellow with the American Bar Foundation and a member of the Harvard Society of Fellows, and has worked as a consultant for Corporate Decisions, Inc. One can be an outsider within such institutions, of course. But much of his economics is mainstream.

So this is how scientists affect snark -- so clinical!

You may have already known why, but, as usual, these guys can pretty much always make anything vaguely interesting, like why brokers typically wait 10 days longer to sell their homes. "It's not that real estate agents are bad. It's just that they're human beings, and human beings respond to incentives," Stephen Dubner says. So does this mean if we wait 20 days to sell, we'll make even more?

- Max Abelson

Freakonomics is the latest in a recent genre of nonfiction book that explains in non-stick prose how the world really works, popularizing a science or scientific insight while forever hitting the reader on the head with how damnably clever the author is. It's the Malcolm Gladwell syndrome, signaled by a Gladwell blurb on the cover of Freakonomics stating that Steven D. Levitt has "the most interesting mind in America"-and by a peculiar typo in the publicity materials for the book referring to "Mr. Gladwell" as the author, rather than Mr. Levitt and his collaborator, Stephen J. Dubner. If you are, say, in the camp of Richard Posner in suspecting that Mr. Gladwell wouldn't have the faintest idea of what an interesting mind is (see Mr. Posner's elegant takedown of Blink in the Jan. 24 issue of The New Republic), this might put you off Freakonomics entirely.

That would be too bad. It's a sloppily organized group of essays on completely unrelated topics, but it's entertaining despite its strenuous efforts to be so. And Freakonomics may be worth the cover price in our real-estate-mad city just for matching up the adjectives in real-estate ads with higher or lower sales prices. Who knew that "granite" is correlated with higher prices and "charming" with lower? Sadly, the original research isn't cited.

Despite its outré title and the authors' use of amusingly unconventional case studies, there's a grim undercurrent to Freakonomics. As they acknowledge, economics is a description of the actual, not the ideal, world, and plenty of economic data suggests that human beings are not so wonderful. For instance, on April 15, 1987, when the I.R.S. began requiring Social Security numbers for dependent children listed on income-tax returns, seven million American kids vanished overnight. Who says it's mainly the rich who are tax cheats?

Mr. Levitt has also found that real-estate agents sell their own houses for over 3 percent more than comparable houses they represent, largely because they don't take the first offer. They'll encourage you to do just that-and even tell buyers that you'll settle for less than the asking price-because waiting for a better offer isn't worth their time: A marginally better price yields pretty much the same commission. Not quite so close to home, Mr. Levitt discovered that cheating, in the form of thrown matches, is rife in sumo wrestling, Japan's most revered sport.

Actually, this book arrives with a minor ethics issue of its own in tow. As announced up front in an "Explanatory Note," two years ago Mr. Dubner wrote a laudatory account of Mr. Levitt for The New York Times Magazine, which aroused publishers' interest in the idea of a book by Mr. Levitt-who then approached Mr. Dubner about a collaboration. One doesn't usually think, when reading a magazine profile, that the author is about to do business with the subject, "rogue economist" or not.

Mr. Levitt's most controversial and most dismal theory is that the abrupt decline in the U.S. crime rate in the late 80's and early 90's is due mainly to the passage of liberalized abortion laws following the Supreme Court's 1973 Roe v. Wade decision. "In the first year after Roe v. Wade, some 750,000 women had abortions in the United States (representing one abortion for every 4 live births). By 1980 the number of abortions reached 1.6 million (one for every 2.25 live births), where it leveled off." The authors argue that a good many of the post- Roe abortions were performed on mothers who were poor, teenage and unmarried; on the evidence of just one study, they conclude that these children had they been born, would have been significantly more likely to grow up to become criminals.

The presentation of this issue in Freakonomics is misleading, in part because the statistics on who gets abortions are a little more complicated than Messrs. Levitt and Dubner imply. First of all, the authors elide the important difference between abortion ratio (relation of abortions to live births) and abortion rate (number of abortions per 1,000 women of childbearing age). Abortion ratio can rise because women start having fewer children, period, as they have in the U.S., even if the abortion rate stays the same. The abortion-rate statistics show an arc, but it's one that returns nearly to pre- Roe levels: The figure in 1972 was 13 per 1,000 women of childbearing age, and 16 per 1,000 in 2000; it peaked at 25 per 1,000 in 1980. The only case where abortion ratios have performed as the authors imply is among black women, rising even as they have fallen among white women: In 1973, 420 per 1,000 live births versus 326 for white women, and in 1997, 543 per 1,000 live births versus 194 for white women.

If Messrs. Levitt and Dubner were right, crime rates would have been at their lowest around the time when the unborn children of 1980 would have been old enough to start breaking the law, but in fact the trend has been downward through the present, for both violent and nonviolent crimes.

It's equally suspect of the authors to imply that the unborn children would have had mainly unmarried teenage mothers. Of the women who had legal abortions in 1972-before Roe made legal abortion widely available-67.4 percent were 20 or older and 29.7 percent were married. Yet in 1980, when by Mr. Levitt's reasoning the women having legal abortions would have been younger and more likely to be single, 70.8 percent of women having abortions were 20 or older, and 23.1 percent were married-not so different, given that marriage rates had been falling at the same time.

The authors' argument has even deeper flaws. The most impoverished, least educated young girls were the ones most likely to have their babies rather than aborting them. The birth rate among unmarried women nearly doubled in the years Messrs. Levitt and Dubner discuss. Unmarried teens from 15 to 19 had a birth rate of 22.4 per 1,000 in 1970, 27.6 in 1980, 42.5 in 1990 and 40.4 in 1999. And it's equally probable that a lot of post- Roe abortions were performed on young girls from middle-class backgrounds who, in the absence of Roe, would have married the men who got them pregnant and raised children who would have gone on to become middle-class, law-abiding citizens.

When one begins to question Freakonomics, cracks in the logic proliferate. About those hasty real-estate agents: In how many cases, one wants to ask, did the seller have a good reason to accept the first offer (maybe because she was trying to buy another house, a terrific bargain, and wanted a quick closing)? Was the study corrected for variation in the sellers' financial position? Presumably some sellers have their house on the market because of money problems; they may even be trying to stave off an anticipated foreclosure. The more questions one asks, the shakier the argument looks.

Perhaps Mr. Levitt is more rhetorician than economist.

The authors proudly trumpet Mr. Levitt's "underlying belief" that "the modern world" is " not impenetrable, is not unknowable." But the problem with Mr. Levitt's problems, as the abortion example shows, isn't that the modern world is unknowable, but that there are too many factors, in many cases, to be sure what the correct explanation for something is. And this is where cleverness must retire in favor of wisdom-which is not in great supply in Freakonomics.

Ann Marlowe, author of How to Stop Time: Heroin from A to Z (Anchor), has a rarely used M.B.A. in finance; her next book will be published by Harcourt in early 2006.

Where were you on Dec. 23, 1972? Stephen Dubner and I were both watching the A.F.C. divisional playoffs on WRGB-NBC. He was in upstate New York, I was in western Massachusetts. His TV was small and black-and-white; mine was small and color. He was 9 and I was 13. He was rooting for the Pittsburgh Steelers, I was rooting for the Oakland Raiders-I liked Kenny (the Snake) Stabler and the tiny, nimble Fred Biletnikoff. The game was tight, a defensive battle-not ideal for young boys-but it was capped off by perhaps the strangest, most memorable play in the history of pro football: the "Immaculate Reception," a freaky, last-second, game-winning touchdown that sent the Steelers to the A.F.C. championship and turned Stephen Dubner into a hero-worshipper. (As for me, it confirmed my budding teenage suspicion that the world was random and absurd.)

Mr. Dubner's rich description of the Immaculate Reception, which began as a desperation pass from the Steelers' quarterback, Terry Bradshaw, and unfurled in a manner that "would have confused even Pythagoras," is worth quoting in its entirety: "The ball zipped downfield where it, one Steeler and one Raider met with great force. Neither man, however, came close to catching the ball. It ricocheted free, seemingly destined to land on the turf and kill the Steelers' season. But the ball, instead of falling to the ground, had somehow remained aloft and now traveled in a wobbly arc back towards the line of scrimmage. Suddenly Franco Harris arrived at full gallop and, cradling his hands as if to rescue a baby tossed from a burning tenement, caught the ball at his shoetops. Never losing stride, he headed for the end zone, shoulders rising and falling in grand fashion, arms and legs pumping fluidly, a Giacometti come to life." You can probably guess two things from the style of the telling: that Franco Harris was about to become an important factor in young Stephen Dubner's imaginative life (rescuing babies from burning buildings! Running like a statue come to life, a male Galatea!), and that when he grew up, Mr. Dubner became a magazine writer. (Extra points if you spotted the signature tics of The New York Times Magazine : here a pulp metaphor, there a highbrow flourish.) (As for me, I became a critic.)

Franco Harris, a rookie in 1972, became a hero to all of Pittsburgh, a town in desperate need, and to Stephen Dubner, a boy in desperate need. Nearly a year to the day after the Immaculate Reception, Mr. Dubner's father died, leaving behind his wife, eight children and no money. Stephen, the youngest Dubner, began having a recurring dream about Mr. Harris. He became infatuated. He cataloged the things he and his hero had in common. He tried unsuccessfully to change his name to Franco Dubner. He worshipped-but not, Mr. Dubner insists, because of his hero's prowess on the football field: "I didn't worship him for what he did; I worshiped him for who he was."

And who was he, this Immaculate Receiver? A wonderful running back-big but delicate, known for skipping out of bounds to avoid a tackle-and a good man, too. Mr. Dubner writes, "He was, in jock parlance, 'a real class act.'" The son of a black G.I. and his Italian bride, young Franco grew up in New Jersey (nine children in the family), showed exceptional promise at Penn State under Joe Paterno, played brilliantly for the Steelers during their decade of glory, and retired well before he became a superannuated embarrassment. He was inducted into the Hall of Fame in 1990. Post-football, he stayed on in Pittsburgh, became a businessman and did nothing to besmirch his reputation as a nice, gentle guy.

And young Stephen Dubner grew up and went to college and forgot about Franco Harris, became a journalist and wrote a book (about how his Catholic parents were actually Jews who converted), and was walking through Times Square (on his way to his job at The New York Times Magazine ) when he saw a photo of Mr. Harris on the cover of Black Enterprise magazine and bam!-the memory of all his youthful hero worship (Franco Dubner!) came flooding back and there it was, all but written, his second book. "I'm interested," he told Mr. Harris within hours of tracking him down, "in the relationship between a hero and a hero-worshiper."

It's perfectly fine, this second book-vivid, cheerful, amusing, only intermittently disturbing and never taxing. There's a feel-good storyline of the healing-journey variety about Mr. Dubner finding himself (his wife has a baby, which makes him a dad), and also a more interesting dark undertow: Mr. Dubner's avid pursuit of his subject is even creepier than he admits (one chapter is called "I Am Not a Stalker"-but he comes awfully close). The fact that Mr. Harris is amiable and decent -about as un-heroic as a meatloaf sandwich-makes for some fine understated comedy.

No, Stephen Dubner is not a stalker. He's something far more dangerous: a journalist. Mr. Harris, though guileless, wasn't fooled for a moment by Mr. Dubner's ardent advances and kept him at a cool distance. True to form, he skipped out of bounds. Professional athletes find out all about journalism the moment they achieve any degree of fame, and at the end of his rookie year, Franco Harris was already a legend. By the time Stephen Dubner came knocking, 30 years after that first media blitz, Mr. Harris could surely have formulated for himself the immortal Janet Malcolm dictum: "Every journalist who is not too stupid or too full of himself to notice what is going on knows that what he does is morally indefensible." The journalist's agenda will mesh with his subject's only by the wildest coincidence. As it happens, Mr. Dubner's motives, though inevitably self-serving were almost wholly benign. In the end, his victim got off easy: Why should Franco Harris, a Pittsburgh businessman in his 50's, object to the world being told that he's really just a good guy?

Adam Begley is the books editor of The Observer.