The New America Foundation report, released Monday, said the majority of cases, traditional law enforcement and investigative methods provided the tip or evidence to initiate the case.
"An in-depth analysis of 225 individuals recruited by al-Qaida or a like-minded group or inspired by al-Qaida's ideology, and charged in the United States with an act of terrorism since 9/11, demonstrates that traditional investigative methods, such as the use of informants, tips from local communities, and targeted intelligence operations, provided the initial impetus for investigations in the majority of cases, while the contribution of NSA's bulk surveillance programs to these cases was minimal," the report said.
The controversial bulk collection of data – leaked to news media in June by former NSA contractor Edward Snowden – "appears to have played an identifiable role in initiating, at most, 1.8 percent of these cases," the report said.
Under the program, the NSA collects metadata -- records of phone numbers dialed, call lengths and times, of virtually every American. The content of calls is not collected.
The presidential task force that reviewed surveillance operations concluded last month the program "was not essential" to preventing terrorist attacks.
On Friday, Obama will announce his proposals to change intelligence operations and oversight that most likely will modify, but not stop, the collection of billions of phone call logs.
New America Foundation said its analysis found the NSA program provided evidence to initiate one case involving a San Diego cabdriver convicted of providing $8,500 to help fund al-Qaida affiliate al-Shabaab in Somalia.
"The overall problem for U.S. counter-terrorism officials is not that they need vaster amounts of information from the bulk surveillance programs," the report said, "but that they don't sufficiently understand or widely share the information they already possess that was derived from conventional law enforcement and intelligence techniques."