Determining what millions of Americans eat is not a responsibility to be taken lightly. In the Big Apple, that charge falls largely to two competing dining guides -- the "Zagat Survey 2005: New York City Restaurants" ($13.95) and "Time Out New York's Eating and Drinking 2005" ($11.95). Which is better equipped to steer the masses through America's culinary capital? New Yorker Seth Sherwood compares.

REVIEWING SYSTEM. The Zagat guide, now in its 26th year, has refined restaurant reviewing into a science. Every year, Zagat surveys thousands of New Yorkers about the places they've eaten. Each respondent rates the establishments in three criteria -- food, decor, service -- on a 30-point scale. Zagat then averages the numbers to determine overall scores. The huge base of reviewers dilutes individual prejudices and minimizes the sway of uncharacteristic aberrations in an eatery's food or service. The numerical ratings allow readers, at least in theory, to quantify the quality of each restaurant and compare it with its rivals.

The Time Out guide, in its sixth year, takes the opposite approach. More literary than scientific, the guide uses no grading systems, relying instead on individual reviewers who write vivid descriptions of each restaurant. But while the reviews are longer, more clever and more descriptive than Zagat's -- which blandly strings together snippets of diners' commentary -- the lack of a weighing system makes it hard to know how restaurants stack up against one another. Moreover, each establishment is visited by only two or three reviewers, so personal bias may creep in.

Advantage: Zagat.

LOGISTICAL INFO. Each Zagat review is accompanied by the restaurant's address, cross street, phone number, Web site and price level. Icons indicate whether the place is open late and takes credit cards. Time Out offers the same info (except Web sites) and heaps on more: hours, nearest subway stops and the specific credit cards accepted. Icons tell if a place is especially cheap or a critical favorite.

Advantage: Time Out.

SCOPE. Zagat reviews 1,946 restaurants, which it breaks down into 93 types of cuisine. Everything from noodle joints to gastronomic temples is covered. All five boroughs are represented, though the focus is clearly on Manhattan and, to a lesser degree, Brooklyn. Fewer than 30 reviews are devoted to the Bronx and Staten Island combined.

Time Out serves up more than 2,000 reviews representing 38 cuisines in a wide range of prices. Though it lacks many specialty categories found in its competitor -- Zagat's attention to Soup, Hot Dogs and Ice Cream Parlors appealed to our late-night cravings -- Time Out shows greater depth in nearly all ethnic cuisines. It also displays a farther geographic reach, pulling in more restaurants from the outer boroughs.

Advantage: Toss-up.

STYLE. As befits a guide built on number-crunching and categorizing, Zagat has as much flash as a middle-aged accountant. Don't expect photos, colors or embellishments -- just facts and figures. Time Out, by contrast, is a fashionista. Dolled up with crisp page design and hundreds of color photos, the guide doesn't just describe food and restaurants, it feeds them to you. Glossy images of sumptuous dishes, sleek dining rooms and sexy local restaurateurs give it the feel of an art book.

Advantage: Time Out.

SIZE: Slender and lightweight, the 286-page Zagat guide can fit into a jacket pocket or purse, making it an easy traveling companion when stepping out for an evening. It's easy to flip through and is quickly referenced. Significantly bigger, bulkier and heavier -- the book's surface area is about twice that of Zagat's -- the 336-page Time Out won't be leaving the house very often.

Advantage: Zagat.

EXTRAS: Zagat bursts with ranked lists. Sure, it lists the big three -- the Top 50 restaurants for food, decor and service -- but it also highlights the top restaurants according to cuisine and neighborhood. The Special Features index tells which restaurants have cheese trays, interesting bathrooms, noteworthy histories, etc.

No ranked lists, but Time Out has a flurry of other bonuses: chef interviews, info sidebars, street/subway maps and a list of the city's best bars. Time Out's editors also offer a primer on decoding wine labels and provide wine recommendations by cuisine.

Advantage: Toss-up.

BOTTOM LINE: Both guides are very useful -- and very different. Get Zagat if you want portability and a quantitative way to compare restaurants quickly and easily. But if size doesn't matter and you feel comfortable with reviews conducted by just two or three folks, Time Out offers wider coverage of New York City's dining scene, more info on each establishment and a snazzier package.

Both guides are available at bookstores and from the Zagat (www.zagat.com) and Time Out (http://eatdrink.timeoutny.com) Web sites.