Life is life, and you gotta do what you gotta do. It's like everybody can't be a doctor, a teacher, or have rich parents take care of us. And it's gonna teach us, like — when we get older, we're gonna be stronger, 'cause we know life experience and stuff like that. And we're goin' to know what to do in certain situations because of what we've been through when we were younger. You gotta do what you gotta do to survive.

— female, age 16

The first night Ric Curtis and Meredith Dank went looking for child prostitutes in the Bronx in the summer of 2006, they arrived at Hunts Point with the windows of Curtis's peeling Oldsmobile, circa 1992, rolled down.

Curtis, who chairs the anthropology department at the John Jay College of Criminal Justice in Manhattan, had done research on the neighborhood's junkies and was well acquainted with its reputation for prostitution (immortalized in several HBO documentaries). If the borough had a centralized stroll for hookers, he figured Hunts Point would be it.

But after spending several hours sweating in the muggy August air, the professor and his PhD student decided to head home. They'd found a grand total of three hookers. Only two were underage, and all three were skittish about climbing into a car with two strangers and a tape recorder.

Dispirited though they may have been, the researchers had no intention of throwing in the towel. They were determined to achieve their goal: Conduct a census of New York City's child sex workers.

Even before they'd begun gearing up for the project two months prior, Curtis and Dank knew the magnitude of the challenge they had on their hands.

No research team before them had hit on a workable method of quantifying this elusive population. For decades, most law-enforcement officials, social workers, and activist groups had cited a vast range — anywhere from tens of thousands to three million — when crafting a sound bite pegging the population of underage hookers nationwide. But the range had been calculated with little or no direct input from the children themselves.

Over time, the dubious numbers became gospel.

In similar fashion, monetary outlays based on the veracity of those numbers began to multiply.

The $500,000 the federal government had allotted for this joint study by John Jay and New York's public-private Center for Court Innovation was chump change compared to the bounty amassed by a burgeoning assortment of nonprofit groups jockeying to liberate and rehabilitate the captive legions of exploited and abused children.

Now Ric Curtis intended to go the direct route in determining how many kids were out there hooking: He and Dank would locate them, make contact with them, and interview them one-on-one, one kid at a time. If the research team could round up and debrief 200 youths, it would be able to employ a set of statistically solid metrics to accurately extrapolate the total population.

It took two years of sleuthing, surveying, and data-crunching, but in 2008 Curtis and Dank gave the feds their money's worth — and then some.

The results of the John Jay survey shattered the widely accepted stereotype of a child prostitute: a pre- or barely teen-age girl whose every move was dictated by the wiliest of pimps.

After their first attempt flopped, the two researchers switched tacks. They printed a batch of coupons that could be redeemed for cash and which listed a toll-free number that kids could call anonymously to volunteer for the survey. With a local nonprofit agency that specialized in at-risk youth on board to distribute an initial set of the coupons, the researchers forwarded the 800 line to Dank's cell phone and waited.

It took almost a week, but the line finally lit up. Soon afterward, Dank met her first two subjects — one male, the other female — at a café near Union Square. Both were too old to qualify for the study, and the man said he'd never engaged in sex for pay. But Dank decided to stay and interview them.

The woman said she had worked as a prostitute and that she was confident she could send underage kids Dank's way. The man said he was 23, just out of jail and homeless.

"Out of the two of them, I thought she would have been the catalyst," Dank says now. "But his was the magic coupon."

Within a day, her phone was "blowing up" with calls from kids who'd been referred by the homeless man. Almost as quickly, word got around that two professors were holding late-afternoon "office hours" at Stuyvesant Park and would pay half the going rate for oral sex in exchange for a brief interview. Before long, the researchers found themselves working long past dark, until they'd covered everyone in line or the rats got too feisty.