A new analysis of the targeted killing of terrorists in Pakistan argues that U.S. drones have injured or killed far more civilians than the U.S. government has acknowledged and questions whether the strikes have been effective in making the U.S. any safer.

The study, by the Stanford and New York University law schools, urges policy makers to "rethink current targeted killing practices" based on evidence of the "damaging and counterproductive effects of current U.S. drone strike policies."

Get more pure politics at ABCNews.com/Politics and a lighter take on the news at OTUSNews.com

White House officials declined to comment on the study, titled "Living Under Drones."

While the authors make clear that drones have killed alleged combatants and disrupted terrorist networks, they question "the efficacy and counter-productive nature" of the strikes. Based on more than 130 interviews with witnesses and foreign policy experts, the authors dissect three separate drone attacks, detailing the personal stories of the victims and offering firsthand testimony from the families they left behind. The study concludes that drone strikes, particularly multiple strikes on one area, cause "under-accounted-for harm" to civilians who escape physical injury. "Their presence terrorizes men, women, and children, giving rise to anxiety and psychological trauma among civilian communities," the report says.

The authors call for more transparency and ask the federal government to make public the legal justification for targeted killing in Pakistan. It also calls for more detail on how the U.S. tracks and publicly recognizes civilian causalities.

But other experts question the accuracy of the data on which the authors rely. While the true number of casualties is hard to obtain, the authors cite data from the Bureau of Investigative Journalism - which The Atlantic's Joshua Foust notes relies heavily on media accounts when compiling its data - that show drones killed between 474 and 881 civilians in Pakistan from June 2004 to mid-September 2012, including 176 children.

Foust, for instance, notes that the 130-person sample size for a country of 175 million "is just not representative. 130 respondents isn't representative even of the 800,000 or so people in the Federally Administered Tribal Areas (FATA), the region of Pakistan where most drone strikes occur. Moreover, according to the report's methodology section, there is no indication of how many respondents were actual victims of drone strikes…. The direct victims they interviewed were contacted initially by the non-profit advocacy group Foundation for Fundamental Rights, which is not a neutral observer (their explicit mission is to end the use of drones in Pakistan)."

Foust concluded that the "Living Under Drones" report "has some serious bias issues. But that doesn't mean it should be discarded: the section on social and political blowback from drone strikes is well documented and in line with other research. In summary, the report declares that the use of drones in Pakistan is a campaign of terror, creating severe psychological trauma among residents of the FATA and creating a pervasive environment of fear."

-Jake Tapper and Mary Bruce