Just found, this was published in January 2014 and originates from the New America’s National Security Program:
...shows the NSA’s bulk surveillance programs have had a negligible impact in preventing terrorism in the United States.....an in-depth analysis of 225 individuals recruited or inspired by al-Qaeda or like-minded groups, and charged with a terrorism-related crime since 9/11. It notes that the contribution of the NSA’s bulk surveillance programs to these cases was minimal compared to more traditional law enforcement methods, which initiated the majority of cases. The report also found that the collection of American phone metadata has had no discernible impact on preventing acts of terrorism and only the most marginal of impacts on preventing terrorism-related activity, such as fundraising.
Nice graphic which will not copy:http://natsec.newamerica.net/nsa/analysis