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The ability of NASA's Mars Reconnaissance Orbiter to continue charting the locations of these hidden glaciers and ice-filled valleys -- first confirmed by radar two years ago -- adds clues about how these deposits may have been left as remnants when regional ice sheets retreated. The subsurface ice deposits extend for hundreds of kilometers, or miles, in the rugged region called Deuteronilus Mensae, about halfway from the equator to the Martian north pole. Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and colleagues prepared a map of the region's confirmed ice for presentation at this week's 41st Lunar and Planetary Science Conference near Houston. The Shallow Radar instrument on the orbiter has obtained more than 250 observations of the study area, which is about the size of California. "We have mapped the whole area with a high density of coverage," Plaut said. "These are not isolated features. In this area, the radar is detecting thick subsurface ice in many locations." The common locations are around the bases of mesas and scarps, and confined within valleys or craters. Plaut said, "The hypothesis is the whole area was covered with an ice sheet during a different climate period, and when the climate dried out, these deposits remained only where they had been covered by a layer of debris protecting the ice from the atmosphere."

Statistical validation of results, as Shaffer described it, simply involves testing the null hypothesis: that the pattern you detect in your data occurs at random. If you can reject the null hypothesis—and science and medicine have settled on rejecting it when there's only a five percent or less chance that it occurred at random—then you accept that your actual finding is significant. The problem now is that we're rapidly expanding our ability to do tests. Various speakers pointed to data sources as diverse as gene expression chips and the Sloan Digital Sky Survey, which provide tens of thousands of individual data points to analyze. At the same time, the growth of computing power has meant that we can ask many questions of these large data sets at once, and each one of these tests increases the prospects than an error will occur in a study; as Shaffer put it, "every decision increases your error prospects." She pointed out that dividing data into subgroups, which can often identify susceptible subpopulations, is also a decision, and increases the chances of a spurious error. Smaller populations are also more prone to random associations. In the end, Young noted, by the time you reach 61 tests, there's a 95 percent chance that you'll get a significant result at random. And, let's face it—researchers want to see a significant result, so there's a strong, unintentional bias towards trying different tests until something pops out. Young went on to describe a study, published in JAMA, that was a multiple testing train wreck: exposures to 275 chemicals were considered, 32 health outcomes were tracked, and 10 demographic variables were used as controls. That was about 8,800 different tests, and as many as 9 million ways of looking at the data once the demographics were considered.

BOLD FARMING: Pesticide used at a marijuana grow site in Sequoia National Park in California is prepared for removal by helicopter. (Photo: Gary Kazanjian/AP) Not far from Yosemite's waterfalls and in the middle of California's redwood forests, Mexican drug gangs are quietly commandeering U.S. public land to grow millions of marijuana plants and using smuggled immigrants to cultivate them.   Pot has been grown on public lands for decades, but Mexican traffickers have taken it to a whole new level: using armed guards and trip wires to safeguard sprawling plots that in some cases contain tens of thousands of plants offering a potential yield of more than 30 tons of pot a year.

Today, he is emerging as one of the nation’s archreformers, pushing to impose some of the most stringent new financial regulations in history. And as the head of the Commodity Futures Trading Commission, the leading contender to oversee the complex derivatives contracts that played a central role in the financial crisis and, in turn, the Great Recession, he is in a position to influence the outcome. It may seem an unlikely conversion, but it is one that has won the approval of Brooksley E. Born, of all people, a former outspoken head of the commission. She sounded alarms more than a decade ago about the dangers hiding in the poorly understood derivatives market and was silenced by the same Washington power brokers that counted Mr. Gensler as a member. Mr. Gensler opposed Ms. Born, according to people who worked at the commission in the 1990s, and in 2000 played a significant role in shepherding through Congress deregulation measures that led to explosive growth of the over-the-counter derivatives market. That was then. These days, Ms. Born is convinced of Mr. Gensler’s reformist zeal, as he takes on Wall Street in what is becoming one of the fiercest battles over regulation in the postcrisis era. “I think he is doing very well,” she said in an interview. “He certainly seems to be committed to robust oversight of derivatives and limiting excessive speculation and leverage.” The proposals championed by Mr. Gensler, if adopted by Congress, would substantially alter what is now a largely unregulated market in over-the-counter derivatives, financial instruments used by companies and investors to protect themselves and bet on moves in variables, like interest rates or currencies, and to speculate. The proposals include forcing the big banks that sell derivatives to conduct their trades in the open on public exchanges and clear them through central clearinghouses, so that any investor can see the prices that dealers charge their customers. Today, those transactions are bilateral and private.

In 1982, the top 1 percent of pop stars, in terms of pay, raked in 26 percent of concert ticket revenue. In 2003, that top percentage of stars — names like Justin Timberlake, Christina Aguilera or 50 Cent — was taking 56 percent of the concert pie.

. In an article entitled “The Economics of Superstars,” he argued that technological changes would allow the best performers in a given field to serve a bigger market and thus reap a greater share of its revenue. But this would also reduce the spoils available to the less gifted in the business.

IF one loosens slightly the role played by technological progress, Dr. Rosen’s framework also does a pretty good job explaining the evolution of executive pay. In 1977, an elite chief executive working at one of America’s top 100 companies earned about 50 times the wage of its average worker. Three decades later, the nation’s best-paid C.E.O.’s made about 1,100 times the pay of a worker on the production line.