There's no shortage of advice for how to use less energy at home, thus saving both money and the planet. For decades, energy-efficiency advocates have tried to convince Americans to replace incandescent light bulbs with compact-fluorescent ones, use hot water sparingly, wait as long as possible before turning on the A/C, and so on. But not all of these tips are created equal: Some appliances and behaviors use more energy than others. How good a grasp do we have on this crucial information?

Recently, a team of researchers led by Columbia University's Shahzeen Attari surveyed 505 people, recruited via Craigslist in seven U.S. metropolitan areas, to find out. The results were published in August in the Proceedings of the National Academy of Sciences. In honor of Earth Day—April 22, 2011—Slatehas collaborated with Attari's team to turn a portion of the study into an interactive quiz. After taking this short survey, you'll receive detailed feedback about how your guesses compare to the best available estimates and how you fared compared to other Slate readers. (Note: Slate has agreed to share the results with Attari; the data contain no personally identifiable information.)

If you're anything like the participants in Attari's study, you probably underestimated a lot of the energy-use figures in the quiz. (The people Attari surveyed guessed these appliances used less than half the energy they really do on average.) You probably also underestimated the differences in energy consumption between devices, an effect known in psychology as "compression bias." That's hardly surprising, and nothing to be ashamed of. Americans pay very little for energy relative to other expenses—just under 11 cents per kilowatt - hour on average —so there's not a great deal of financial incentive to learn how many watts a portable heater, for instance, draws from the wall. And while automakers advertise their cars' fuel-efficiency ratings, a dishwasher's wattage is rarely it's selling point.

The use of a light bulb as the starting reference point is another, more controversial reason you might have low-balled your estimates. When another team of researchers used a 9,000-watt electric furnace as the reference point, they found that people overestimated energy use by a factor of 1.6. (This phenomenon is known as the "anchoring effect.") They published a somewhat critical letter to this effect in PNAS; Attari's team responded that anchoring effects are unavoidable and that a 100-watt bulb is a far more natural (and common) reference point than a furnace.

Cursed with poor instincts for energy use, what's an eco-conscious citizen to do? Unfortunately, we're fettered by a dearth of reliable, up-to-date information on appliances' energy use. It's a service that you'd think the Department of Energy, so determined to promote energy efficiency, would provide, but they don't. Neither do big-box retailers with the resources and incentive — energy-efficient appliances typically cost more up-front, but then pay for themselves over time. Instead, Attari points readers to Gerald Gardner and Paul Stern's The Short List, a "prioritized, accurate, accessible, and actionable list of the most effective household actions to help limit climate change." If all households followed Garnder and Stern's recommendations, these actions could reduce total U.S. energy consumption by 11 percent and national national carbon emissions by more than 7 percent over 10 years.